Domain 3 Diagnosing and Troubleshooting

CompTIA A+ Exam Objectives Covered in This Chapter

  • 3.1 Recognize and interpret the meaning of common error codes and startup messages from the boot sequence, and identify steps to correct the problems
  • 3.2 Recognize when to use common diagnostic utilities and tools. Given a diagnostic scenario involving one of these utilities or tools, select the appropriate steps needed to resolve the problem.
  • 3.3 Recognize common operational and usability problems and determine how to resolve them

The general theme of the third domain of the A+ Operating System objectives is troubleshooting. Topics range from how to best get information out of users about what problem they are having to how to research or solve some of the more common problems.

Being able to troubleshoot problems—to find out what is wrong with a particular system— is one of the most basic job requirements of a technician. Rarely does a user send a machine in for repair with a note that says, “WIN.COM file is missing.” or “The network card driver is corrupt.” They just bring in a computer, give a basic description of what is happening (“My computer doesn’t work” is a common one), and leave it up to you to decipher what is wrong and fix it. You will soon learn, by the way, that chatting with the user a bit can often turn up valuable information, and we’ll cover how to do that as well.

This domain includes three sections. The first deals with the particular problem of troubleshooting the boot process, and the second deals with more general system troubleshooting and diagnostics. The third objective focuses on operational and usability problems and how to resolve them.

Recognizing and Correcting Boot Sequence Errors

This objective covers some of the more common problems that can appear during startup. We will examine these problems and explain how you can find information about what is causing you trouble.

Critical Information

Normally, if there is a problem with Windows, it becomes apparent during the startup process. This content area looks at problems that either keep the system from starting or cause the startup to be abnormal.

Common Error Messages and Codes

Interpreting the error messages that appear on-screen is the first step in troubleshooting startup problems. Here are some of the more common errors you might see at startup. The exam objectives divide them into some rather arbitrary categories, but we will address them all together:

Invalid Boot DiskYou’ll see this error when the disk the system is trying to boot from doesn’t have the needed files. One of the most common causes of this error is accidentally leaving a nonbootable floppy in the drive when you reboot. Remove the floppy and try again.

If there is no floppy in the drive, perhaps one of the startup files has been removed from the hard disk. If it’s a Windows 9x system, boot from your startup floppy and use the SYS C: command to retransfer the system files to the hard disk. If it’s an NT-based system, use the Windows Setup CD in Repair mode.

No Operating SystemThis error means the computer’s BIOS checked all the drives it knew about and couldn’t find any disk with a bootable sector. There could be any number of reasons for this error, including the following:

  • An operating system wasn’t installed.
  • The boot sector has been corrupted.
  • The boot files have been corrupted or deleted.

If there is a problem with the boot sector, you might try the FIXBOOT command from the Recovery Console (Windows 2000/XP) to repair it. You will probably end up needing to reinstall Windows.

Inaccessible Boot DeviceThis error can occur if the normal boot device is not available for some reason. For example, perhaps a workstation is set to boot from a network drive that is not currently available. To fix it, make the boot device available again by troubleshooting why the system cannot access it. Perhaps the problem is a loose cable or a physical failure of the drive.

Missing NTLDRThis error is just what it sounds like: NTLDR is missing, so Windows NT, 2000, or XP cannot boot. You can run Windows Setup in Repair mode to fix it, or you can try copying NTLDR from another PC.

Bad or Missing COMMAND.COMThis error occurs on an MS-DOS or Windows 9x system when the COMMAND.COM file is deleted from the root directory of the boot drive or is corrupted. Replace it from another PC, or boot to the startup floppy and use SYS C: to replace it. This error can also occur when you accidentally leave a floppy disk in the PC that was a bootable disk at one time (and hence still has IO.SYS and MSDOS.SYS on it) but has had COMMAND.COM deleted.


Remember that the system files for each version of Windows are different. When you’re replacing a file, make certain you are using a replacement from the correct OS—and the correct version of that OS. If you have applied a patch or a Service Pack to a system, you need to get the proper files for that Service Pack level.

HIMEM.SYS Not Loaded, or Missing or Corrupt HIMEM.SYSHIMEM.SYS is the extended memory manager. If it is missing or corrupted, or can’t be loaded, Windows can’t load. Before you panic, try doing a cold reboot of the system—that is, shut off its power, wait a few seconds, and turn it back on. Sometimes problems with HIMEM.SYS not loading resolve themselves this way. If that doesn’t work, replace HIMEM.SYS from another computer or from the Windows Setup CD.

Error in CONFIG.SYS Line XXCONFIG.SYS exists only for backward compatibility with MS-DOS applications, so an error in it is usually not a big deal. This error occurs when the system cannot find a driver or command that is being called from CONFIG.SYS. You can live with the error, or you can edit CONFIG.SYS using Notepad or EDIT to remove the offending line.

Device Referenced in SYSTEM.INI, WIN.INI, Registry Is Not FoundThis is mostly the same as an error in CONFIG.SYS, except it’s an error in one of these other files. SYSTEM.INI and WIN.INI exist only for backward compatibility with Windows 3.x, so errors in them are not critical. You can edit those files with the SYSEDIT utility (from the Run command).

Errors in the Registry, however, can be problematic. If the system boots despite the error, you may be able to disable the offending line through the System Configuration Editor (MSCONFIG from the Run command). That method is preferable to manually editing the Registry with REGEDIT, because it is safer.

Device/Service Has Failed to StartThis error means that some device or service referenced in the Registry was not available. It could be as simple as an unplugged device, and it is usually not a critical error that prevents booting. If the device or service is necessary, first check that it is physically operational (for a device) and then try reinstalling its driver.

Windows Protection ErrorA Windows protection error is a condition that usually happens on either startup or shutdown. Protection errors occur because Windows 9x cannot load or unload a virtual device driver (VxD) properly. Thankfully, this error usually tells which VxD is experiencing the problem, so you can check to see if the specified VxD is missing or corrupt. If it is, you can replace it with a new copy. Often this error occurs when a piece of software is improperly uninstalled or when the uninstall program does not completely remove Registry or INI file references. In such a case, you need to either remove the references to the file to complete the uninstall or replace the file to regain the functionality of the virtual device.

Problems with User-Modified Settings

Sometimes users do things to make their systems not boot anymore, and you need to be aware that the problem might have been user-created. For example, sometimes users delete files that need to remain because they don’t know what they are.

When you’re troubleshooting, it is important to communicate with the end user and find out what he did immediately before the problem began. It might not have any relationship to the problem, but then again it might.

If you determine that the problem was caused by something the user did, such as install a poorly written application, you can try System Restore (Windows Me/XP only) to return it to its previous condition, or copy the missing file(s) from another PC.

Using the Correct Utilities

This exam objective specifically mentions three utilities you should study: Dr. Watson, a boot disk (which is not a utility but a disk that contains a collection of them), and Event Viewer.

Dr. Watson

Most Windows versions include a utility known as Dr. Watson. This utility intercepts all error conditions and, instead of presenting the user with a cryptic Windows error, displays information that can be used to troubleshoot the problem. In addition, Dr. Watson logs all errors to log files stored in the WINDOWSDRWATSON directory. Here’s the catch—it only works if you keep it running, because you never know when an error is going to occur. You can run it with the Run command by typing DRWATSON.

Boot Disk

The startup boot floppy that you create with Windows 95/98/Me contains many useful utilities for troubleshooting system problems and rebuilding a system when required. For example, suppose you cannot boot from the hard disk. You might do the following:

  1. Boot from your Windows 9x startup floppy and enable CD support when prompted.
  2. Type C: to make the root directory of the hard disk the active drive letter. If you see a C:> prompt, you know the hard disk is still accessible. If an error appears, you know the hard disk is not accessible.
  3. If possible, use the SCANDISK utility to check the hard disk for filesystem errors.
  4. Type FDISK to start the FDISK utility, and use it to examine the partition information. From this, you can determine whether a valid FAT or FAT32 partition still exists on the hard disk. If it does not, you know the drive has lost everything; if it does, something is preventing it from being seen by the operating system.
  5. If you had to recreate the partitions in FDISK, reboot. Then use the FORMAT utility to reformat the hard disk.
  6. Use the SYS utility to transfer the boot files for the OS to the hard disk if desired. If you are going to reinstall Windows on it, this step is not necessary.

This is just one example scenario for using a boot disk. Every troubleshooting situation is different and will require different measures.

Event Viewer

Windows NT/2000/XP include an Event Viewer utility that tracks all events on a particular Windows NT/2000/XP computer through log files. Event Viewer is shown in Figure 9.1. Anyone can view events, but you must be an administrator or a member of the Administrators group to modify or clear Event Viewer.

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Figure 9.1: Windows 2000 Event Viewer

To start Event Viewer, log in as an administrator (or equivalent) and go to Start Settings Control Panel Administrative Tools Event Viewer. From here you can view the three log files within Event Viewer:

SystemDisplays alerts that pertain to the operation of Windows. System startup information, problems with NT services, and other general health and status events are recorded here.

ApplicationLogs server application errors. Any application that is designed to send log information to NT/2000/XP writes its data here. Examples include antivirus programs and database programs, although not all such programs are designed to use the Application log.

SecurityLogs security events, such as login successes and failures. It also allows administrators to audit the use of files or printers. By default, security logging is turned off, and this log file will be empty unless security auditing has been explicitly enabled.

These log files can give you a general indication of a Windows computer’s health, and it is important that they be available in case of trouble.

There are a couple of possible log problems. One is that the log files can become corrupted. In such a case, you need to delete the log files and let Windows re-create them.

In addition, the Event Viewer log files can fill up, in which case the log cannot add new information. There are two solutions to this problem. The first is to enable circular logging, which allows the system to delete old events as new ones are added. In most cases, this solution works well, but valuable troubleshooting information can be lost.

The other solution is to back up and clean out the log files occasionally. Doing so allows you to keep a record of all events, but it requires more work. To do this, use Event Viewer to save each of the log files, and then choose Clear All Events from the Log menu. This erases all events in the current log file, allowing you to see new events more easily when they occur. Another option, of course, is to increase the size of the logs, which can also be done through Event Viewer.

Failure to Start the GUI

Occasionally, the Windows GUI won’t appear. The system hangs just before the GUI appears. Or, in the case of NT versions, the Blue Screen of Death (BSOD)—not a technical term, by the way—appears. (The BSOD is another way of describing the blue-screen error condition that occurs when Windows NT/2000/XP fails to boot properly or quits unexpectedly.) In Windows 9x, instead of a BSOD, you get a black screen (usually with a blinking cursor in the upper-left corner) that indicates a problem.

Because the device drivers for the various pieces of hardware are installed at this stage, if your Windows GUI fails to start properly, more than likely the problem is related to a misconfigured driver or misconfigured hardware. Try booting Windows in Safe Mode to bypass this problem. Alternatively, some of the files necessary for the GUI may be having problems, and you may need to replace WIN.COM or other system files from the WINDOWS or WINNT directory.

Exam Essentials

Know how to identify common startup problems and recover from startup errors.This includes knowing which files are needed to boot Windows 9x, NT, and 2000, as well as what steps should be taken to bring back these files.

Know which system files can be modified and what they do.These include AUTOEXEC.BAT and CONFIG.SYS, INI files, and the NT/2000/XP BOOT.INI file. Know how to use a text editor to modify these files.

Know how to deal with Windows error messages.Understand how Dr. Watson works in shutting down and controlling problems and how Event Viewer and other files record information useful for troubleshooting.

Using Common Diagnostic Utilities and Tools

This objective tests your knowledge of the utilities that come with Windows. It also includes coverage of the various Windows startup modes, although this seems odd because they are also covered under objective 3.1 and are not really utilities. Finally, it covers customer interaction skills such as how to elicit problem symptoms from customers.

Critical Information

The key to studying this objective is not necessarily to have in-depth knowledge of each of the areas, but to be able to apply critical thinking toward a problem and use your familiarity with the list of tools available to select the proper tool. For example, the test will not ask you about the minute details of MSD in terms of keystrokes, but you should know what MSD is and be able to say, in a given situation, whether MSD would help you solve the problem.

Startup Disks

Recall from Chapter 8 that Windows 9x can create startup floppy disks that contain boot files and a collection of utility programs for troubleshooting and repairing a system when Windows will not start. This is possible in Windows 9x because these versions are built on a DOS foundation—they have a DPMI (DOS protected mode interface). This isn’t possible in NT versions of Windows because there is no command-line underpinning.

The files required for a Windows 9x startup disk are IO.SYS, MSDOS.SYS, and COMMAND.COM. The first two must reside in the first data cluster on the disk, so if you ever make a boot disk manually, you must place these system files on the disk with the SYS command rather than copying them there.

The startup disks created in Windows 98/Me include CD-ROM support. That is, they include a variety of generic CD drives that each attempt to load from CONFIG.SYS when you boot from the disk. One of them will work (or so the theory goes). Then MSCDEX.EXE will load from AUTOEXEC.BAT, and you will have real-mode CD-ROM drive support from the command prompt.

Startup Modes

When Windows won’t start properly, it is sometimes due to a driver or some piece of software that’s not loading correctly. To fix problems of this nature, you should first try to boot Windows in Safe Mode. In Safe Mode, Windows loads a minimal set of drivers (including a VGA-only video driver) so that you can disable an offending driver to keep it from loading—and from failing again.

To start Windows in Safe Mode, press the F8 key when you see the Starting Windows display during Windows bootup. Doing so brings up a menu that allows you to start Windows in Safe Mode. Once you’ve booted in Safe Mode, you can uninstall any driver you suspect is causing a Windows boot problem or reinstall the driver if you suspect it is corrupted. Upon reboot, the system should go back to normal operation (non–Safe Mode).


A corrupt driver is one in which the software files for the driver have been damaged. This can be caused by a disk error, by a virus, or by standard “act of God” problems such as power outages.

Both Windows 9x and Windows 2000 offer Safe Mode. Windows NT does not. You can also use the F8 menu in 9x or 2000 to select other boot options, such as logging all messages to a log file during boot, booting to a command prompt, or starting Windows in Safe Mode with network support. The Windows 2000 options include those in the following list. Windows 9x offers similar options, but with differences based on the version:

Safe ModeStarts Windows 2000 using only basic files and drivers (mouse, except serial mice; monitor; keyboard; mass storage; base video; default system services; and no network connections). Once you’re in Safe Mode, you can restore files that are missing or fix a configuration error.

Safe Mode with NetworkingSame as Safe Mode, but tries to load networking components as well.

Safe Mode with Command PromptSimilar to Safe Mode, but doesn’t load the Windows GUI. Presents the user with a Windows 2000 command-prompt interface.

Step-by-Step ModeSimilar to normal booting, except it asks you for a Yes/No answer to each step of the process. This mode is useful for excluding a certain item that you suspect is causing a problem.

For the test, know what all of the Safe Mode options are and which problems Safe Mode can (and can’t) allow you to correct.

Diagnostic Resources

When you are stumped by a computer problem, where do you turn? The exam objectives specify that you should know about the following resources:

User/Installation ManualsConsult the manuals that came with the hardware and software.

Internet/Web ResourcesConsult the websites of the companies that make the hardware and software. Updates and patches are often available for download, or the websites may be knowledgebases of troubleshooting information.

Training MaterialsIf you have taken a class pertaining to the hardware or software, consult the materials you received for that class.

Diagnostic Tools and Utilities

A big part of being a successful technician is knowing what tools are appropriate to correct which problems. The exam objectives specifically mention familiarity with these tools:

Task ManagerLets you shut down nonresponsive applications selectively in all Windows versions. In Windows 2000/XP, it does much more, allowing you to see which processes and applications are using the most system resources. To display Task Manager, press Ctrl+Alt+Delete. It appears immediately in Windows 9x; in Windows 2000/XP, you must click the Task Manager button to display it after pressing Ctrl+Alt+Delete. Use Task Manager whenever the system seems bogged down by an unresponsive application.

Dr. WatsonCovered under objective 3.1; enables detailed logging of errors. Use it whenever you think an error is likely to occur (for example, when you’re trying to reproduce an error).

Boot Disk with CD-ROM SupportThis is not really a utility, but just a reminder that the Windows 9x startup disks contain utilities you can use for troubleshooting. Use one when the system will not boot to Windows (even in Safe Mode).

Event ViewerAlso covered under objective 3.1; it enables you to see what’s been going on behind the scenes in Windows NT/2000/XP. Use Event Viewer when you want to gather information about a system or hardware problem.

Device ManagerAnother utility that has already been covered in this book in greater detail (see objective 2.4). Device Manager shows you what hardware is installed and lets you check its status. Use this when a device is not functioning and you are trying to figure out why.

WinMSDAnother name for System Information, the same utility you can select from the System Tools menu. (Running it at the Run command with WINMSD is an alternative.) WinMSD provides comprehensive information about the system’s resource usage, hardware, and software environments. Use it when you need to gather information about the system.

MSDThe MS-DOS version of System Information. It shows resource allocation, memory usage, and more. Running on today’s fast computers, however, it may show incorrect information because it was designed for much slower PCs with much less RAM and smaller hard disks.

Recovery CDSome computers that come with Windows preinstalled do not come with a full version of Microsoft Windows; instead they come with a Recovery CD that can be used to return the PC to its original factory configuration. The important thing to know about these Recovery CDs is that they wipe out all user data and applications. Use one only when you cannot restore system functionality in any less-drastic way.

CONFIGSAFEA third-party utility for backing up system configuration data. For information about it, see It is odd that the A+ exam objectives mention it, because generally they do not mention other third-party utilities.

Dealing with Customers

Talking to the user is an important first step in the troubleshooting process. Your first contact with a computer that has a problem is usually through the customer, either directly or by way of a work order that contains the user’s complaint. Often, the complaint is something straightforward, such as “There’s a disk stuck in the floppy drive.” At other times, the problem is complex, and the customer does not mention everything that has been going wrong.

Eliciting Problem Symptoms from Customers

The act of diagnosis starts with the art of customer relations. Go to the customer with an attitude of trust: Believe what the customer is saying. At the same time, go to the customer with an attitude of hidden skepticism, meaning don’t believe that the customer has told you everything. This attitude of hidden skepticism is not the same as distrust, but just remember that what you hear isn’t always the whole story, and customers may inadvertently forget to give some crucial detail.

For example, a customer may complain that his CD-ROM drive doesn’t work. What he fails to mention is that it has never worked and that he installed it himself. On examining the machine, you realize that he mounted it with screws that are too long and that these prevent the tray from ejecting properly.

Having Customers Reproduce Errors as Part of the Diagnostic Process

The most important part of this step is to have the customer show you what the problem is. The best method I’ve seen of doing this is to ask them, “Show me what ‘not working’ looks like.” That way, you see the conditions and methods under which the problem occurs. The problem may be a simple matter of an improper method. The user may be doing an operation incorrectly or doing the process in the wrong order. During this step, you have the opportunity to observe how the problem occurs, so pay attention.

Identifying Recent Changes to the Computer Environment

The user can give you vital information. The most important question is, “What changed?” Problems don’t usually come out of nowhere. Was a new piece of hardware or software added? Did the user drop some equipment? Was there a power outage or a storm? These are the types of questions you can ask a user in trying to find out what is different.

If nothing changed, at least outwardly, then what was going on at the time of failure? Can the problem be reproduced? Can the problem be worked around? The point here is to ask as many questions as you need to in order to pinpoint the trouble.

Using the Information

Once the problem or problems have been clearly identified, your next step is to isolate possible causes. If the problem cannot be clearly identified, then further tests will be necessary. A common technique for hardware and software problems alike is to strip the system down to bare- bones basics. In a hardware situation, this could mean removing all interface cards except those absolutely required for the system to operate. In a software situation, this may mean booting up with the CONFIG.SYS and AUTOEXEC.BAT files disabled, or disabling elements within Device Manager.

Generally, then, you can gradually rebuild the system toward the point where the trouble started. When you reintroduce a component and the problem reappears, you know that component is the one causing the problem.

Let me make one last point in this brief introduction to troubleshooting: You should document your work. If the process of elimination or the process of questioning the user goes beyond two or three crucial elements, start writing them down. Nothing is more infuriating than knowing you did something to make the system work but not being able to remember what it was.

Exam Essentials

Know how to create and use a startup disk.Refer back to Chapter 8 as needed for specifics. You should be able to make a startup disk, boot from it, and access its utilities.

Understand how Safe Mode works in Windows 9x and 2000.Knowing when to use Safe Mode can help you recover from numerous problems, primarily driver troubles. Understand the differences between the various Safe Mode options and when each is appropriate.

Identify the appropriate utility for a situation.Given a troubleshooting scenario, you should be able to tell which utility would most likely help you identify the problem, and why it is appropriate.

Know how to deal with customers.The ability to talk to—and listen to—customers is critical to your success as a technician. Learn how to ask questions tactfully. “Why would you do something so stupid?” will not reveal the information you need.

Know where to find answers. Understand how Help, FAQs, and other support options can assist you in finding answers.

Recognizing and Resolving Common Operational and Usability Problems

This objective deals with specific problems, including printing, system errors, network connection problems, and viruses. Given a particular error, you should know what types of troubleshooting procedures are likely to help narrow down and solve the problem.

Critical Information

This objective breaks down its topics into three main sections: printing problems, other common problems, and viruses. We will look at them that way in the following review materials as well.

Troubleshooting Printing

Printers are one of the most important things to become proficient with, because printer problems are generally mission-critical for users. A number of things can go wrong with printers, many of which have nothing to do with software or configuration.

Troubleshooting Windows-Specific Printing Problems

A number of different printer-related issues can cause a PC to require service. Some of the general problem areas include the following:

Printer Hardware ProblemsSometimes you have a problem with physical printer hardware— something is broken, a paper jam occurs, and so on. This is not something that is covered in the A+ OS exam, because hardware issues are covered in the Core Hardware exam.

“Out of” ErrorsIt is sad to say, but these are by far the most common printer problems. Paper, toner, or ink supplies are depleted, and the printer therefore does not produce as hoped. Again, this is not covered in the A+ OS exam.

Problems with PC or Cable HardwareIt is also possible that the computer’s printer port is malfunctioning or that the printer cable is either disconnected or damaged. In such a case, you need to either replace or reattach the cable or check out the PC’s printer port. Again, though, this is not information for the A+ OS test.

If none of these seems to be the problem, then you need to start looking for OS issues—and these issues are covered during the A+ OS exam. Following are a number of problems that may come up.

Incorrect/Incompatible Driver for Print

The print driver is the crucial software for configuring—and therefore for troubleshooting— printer problems. Each printer has a particular set of features and implements them through its own specific driver. Because of this, in order to function properly, a printer must be matched with its proper driver. Incorrect drivers may be designed for a completely different printer or may be outdated software.

If the driver that is installed for a printer is not even close, print jobs sent to the printer normally come out as nothing more than a garbled mess of odd characters. If the driver is close, but not exact, only certain elements—such as color or particular fonts—may be a problem. In either case, the solution is to obtain and install an updated driver, using the Advanced tab of the printer’s Properties page, as shown in Figure 9.2.

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Figure 9.2: Printer Properties Advanced tab showing the New Driver button

Another common source of printer driver errors is corruption of the driver. If a printer driver does not appear to be properly processing information, and you have verified that the driver is the proper version, you can delete the printer from the Printer Settings window and reinstall it.

A quick way to test the printer functionality is to use the Print Test Page option. This option is presented as the last step when you’re setting up a new printer in Windows. Always select this option when you’re setting up a new printer so you can test its functionality. To print a test page for a printer that’s already set up, look for the option on the printer’s Properties menu.

After the test page has been sent to the printer, the computer will ask if it printed correctly. For the first few times, you’ll probably want to answer No and use the Troubleshooting Wizard that appears; but after you have troubleshot a few printer problems, you may prefer to answer Yes and bypass the wizard, which is rather simplistic.

Print Spool Is Stalled

One of the most important features of the screen shown in Figure 9-2 is the middle section, containing the spool settings. This section allows you to configure whether Windows spools print jobs. For some printers there may be a Spool Settings button that opens these options in a separate dialog box instead of this section.

If print jobs are spooled, every time you click Print in a program, the job is printed to a spool directory (usually a subdirectory of the C:WINDOWSSPOOL directory) by a program called SPOOL32.EXE. Then the job is sent to the printer in the background while you continue to work. From the Advanced tab shown in Figure 9.2, you can choose either Spool Print Documents so Program Finishes Printing Faster or Print Directly to the Printer. Choose the appropriate option and click OK. Once you have made changes to a printer, click OK on the Properties page to save them.

Incorrect Parameter

Each printer driver may have any of a number of additional settings, and depending on how these are configured, any number of problems may occur. For the A+ exam, remember that you are not expected to know how to set the particular properties for a printer. There are just too many of them! This is the sort of thing that experience will teach you, but that you won’t be tested on.

Other Common Problems

This chapter has talked about startup problems, printer problems, and system errors. Now it is time for the grab bag of troubleshooting information. These are additional trouble areas you need to know about for the test.

General Protection Faults

A General Protection Fault (GPF) is probably the most common and most frustrating error. A GPF happens in Windows when a program accesses memory that another program is using or when a program accesses a memory address that doesn’t exist. Generally, GPFs are the result of sloppy programming. A simple reboot usually clears the memory. If GPFs keep occurring, check to see which software is causing them. Then find out if the manufacturer of the software has a patch to prevent it from failing. If not, you may want to consider another software package.

Windows Protection Error

A Windows protection error typically occurs because Windows 9x could not load or unload a virtual device driver properly. The error message usually reports which VxD is causing the problem, so you can check to see if the specified VxD is missing or corrupt and replace it with a new copy from the original application disk.

Illegal Operation

Occasionally, a program quits for no apparent reason and presents you with a window that says This program has performed an illegal operation and will be shut down. If the problem persists, contact the program vendor. An illegal operation error usually means that a program was forced to quit because it did something Windows didn’t like. It then displays this error window. The name of the program that has been shut down appears at the top of the window. Use the Details button to view the details of the error. Details include which module experienced the problem, the memory location being accessed at the time, and the registers and flags of the processor at the time of the error.

Illegal operations can happen due to nothing more than a glitch and often do not reappear. Some illegal operations, however, are chronic, and in this case it is likely that some sort of hardware or software incompatibility (or conflict) is the problem. Also, this is the error that Windows NT/2000/XP reports when DOS applications try to access hardware directly, which is not allowed on those systems. In such a case, you cannot run these programs on NT/2000, and you’ll need to find a Windows 9x machine or buy an NT/2000/XP version of the software.

Invalid Working Directory

Some Windows programs are extremely processing-intensive. These programs require an area on the hard disk to store their temporary files while they work. This area is commonly known as a working directory; its location is usually specified during that program’s installation and can be accessed by examining the properties of the application’s shortcut icon, as shown in Figure 9.3. If that directory changes after installation, or if the working directory is deleted, Windows will report an error that says something such as Invalid working directory. The solution is to either reinstall the program with the correct parameters for the working directory or create the directory the program is trying to point to.

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Figure 9.3: A working directory

Some programs use a unique directory as their working directory, whereas others do not specify any working directory at all and instead just use the system default (normally TEMP). In NT-based versions of Windows, you may find that permissions restrictions on the filesystem cause a user to not have access to the directory an application tries to write temporary information to. Because the permissions of the application are an extension of the permissions of the logged-on user, this situation can also produce this error.

System Lockup

It is obvious when a system lockup occurs—the system stops responding to commands and stops processing completely. System lockups can occur when a critical system file is corrupted or when an application issues an instruction that the OS interprets as a STOP error—a dangerous system event. Often, lockups occur because two applications have attempted to access the same critical resource simultaneously. Although system lockups were common in Windows 3.x and happened occasionally in Windows 9x, they are rare in NT versions of Windows.

The remedy for a system lockup is to reboot. However, if the lockups are persistent, the machine may have a serious hardware-related problem or need to have its software reinstalled to repair corrupt files.

Option (Sound Card, Modem, or Input Device) Will Not Function

When you are using Windows, you are constantly interacting with some piece of hardware. Each piece of hardware has a Windows driver that must be loaded in order for Windows to be able to use it. In addition, the hardware has to be installed and functioning properly. If the device driver is not installed properly or the hardware is misconfigured, the device won’t function properly. Common reasons for hardware to not work include:

Hardware Is NonfunctionalReplace the device.

Hardware Is Not Properly Connected to the ComputerCheck connections or reseat the device in its slot or port.

Device Is Not Detected by Plug and PlayThis can be a symptom of any of a number of problems. The connection port the device is using may be disabled. A printer on LPT1 won’t be detected if LPT1 is disabled. Also, the device itself may not be PnP-compliant. In such a case, you have to install it by specifying all drivers and resource settings.

Resource ConflictsIn newer machines, most devices are PCI, and the PCI architecture allows resource sharing between PCI devices using a resource pool idea. Older ISA devices do not have this option, and if two devices try to use the same interrupt or I/O address, one or possibly both of them will be unusable. This is probably the most common reason for problems with hardware in older machines.

Be ready for problems like this on the test, where you will be asked how to diagnose problems with Windows and hardware access. Problems installing or configuring new hardware are among the most common reasons for a machine to be sent in for service.

Application Will Not Start or Load

Once an application is successfully installed, you may run across a problem getting it to start properly. This problem can come from any number of sources, including an improper installation, software conflict, or system instability. If your application was installed incorrectly, the files required to properly run the program may not be present, and the program can’t function without them. If a shared file that’s used by other programs is installed, it could be a different version than what should be installed that causes conflicts with other programs. Finally, if one program fails, it can cause memory problems that destabilize the system and cause other programs to crash. The solution to these problems is to reinstall the offending application, first making sure that all programs are closed.


One of the primary improvements of the 32-bit architecture is the ability to isolate applications from each other and from the OS. This makes it less likely that the failure of one application will affect the entire system.

Cannot Log On to Network (NIC Not Functioning)

If your computer is hooked to a network (and most computers today are), problems that prevent the PC from accessing the network are frequent. In most cases, the problem can be attributed to the following:

Malfunctioning Network Interface CardIf you have checked everything and you can’t get the card to initialize, it may be bad. Replace it, or try it in another machine.

Improperly Installed or Configured Network SoftwareIf you do not have the proper combination of driver/protocol/client, then you won’t be able to access network resources. For a scenario in which the NIC appears to not be functioning, the problem is usually that the NIC driver is incorrect. It is also possible that the NIC driver has been configured improperly—perhaps it is set to 100Mbps and is on a 10Mbps network. The Advanced tab for the NIC displays any of these settings that are available, as shown in Figure 9.4.

click to expand
Figure 9.4: The Advanced Properties window for a NIC

Corrupt Network SoftwareAs always, the files could be bad. Before you try much else, reinstall the drivers for the NIC.

The biggest indicator in Windows that some component of the network software is nonfunctional is that you can’t log on to the network or access any network service. You may not even see the Network Neighborhood on the Desktop. To fix this problem, you must first fix the underlying hardware problem (if one exists), and then properly install or configure the network software.

TSR (Terminate and Stay Resident) Programs

In the days of DOS, there was no easy way to run a utility program in the background while you ran an application. Because necessity is the mother of invention, programmers came up with Terminate and Stay Resident (TSR) programs. These programs are loaded from the AUTOEXEC.BAT file and stay resident in memory until called for by some key combination. Unfortunately, although that approach works for DOS, Windows 95 has its own method for using background utilities. If any DOS TSR programs are in memory when Windows 9x is running, they can interfere with the proper operation of Windows programs. Before you install Windows 9x, make sure that any DOS TSRs are disabled in the AUTOEXEC.BAT file. Whereas Windows 9x doesn’t like TSRs, Windows NT/2000/XP will not run them at all. TSRs have been replaced in NT/2000/XP by services, which are far more stable and efficient.

Applications Won’t Install

We’ve all experienced this frustration: You are trying to install the coolest new program and, for whatever reason, it just won’t install properly. It may give you one of the previously mentioned errors or a cryptic installation error. If a software program won’t install and it gives you an error such as a GPF or illegal operation error, use the solutions for those errors first. If the error that occurs during the install is unique to the application being installed, check the application manufacturer’s website for an explanation or update. These errors generally occur when you’re trying to install over an application that already exists or when you’re trying to replace a file that already exists but that another application has in use.

When you’re installing an application, it is extremely important that you quit all running programs before installing so that the installer can replace any files it needs to. Also, some programs are written specifically for Windows 98 or Windows NT and will not run on any other OS. Make sure that the hardware and OS on which you are installing the application are supported.

Network Connection

If the machine will not attach to the network, but you are certain that the NIC is functional and properly configured, it is very possible that the network resource you are attempting to find is having problems or that the network itself is down. In this case, you should contact the network administrator to see if there are problems. We’ll cover other network-related configuration settings in domain 4.

Viruses and Virus Types

Most computer problems come in one of two sorts: accidents (hardware goes bad or software corrupts) or self-inflicted wounds (user deletes files or changes something). There is one other option, though. For reasons entirely their own, some people with strong computer knowledge use that knowledge to create programs called viruses that can damage your computer software— and potentially even your hardware.

What They Are

A computer virus is a program that replicates itself to other computers, usually causing the computers to behave abnormally. Generally speaking, a virus’s main function is to reproduce. A virus attaches itself to files on a hard disk and modifies the files. When these files are accessed by a program, the virus can infect the program with its own code. The program may then, in turn, replicate the virus code to other files and other programs. In this manner, a virus can infect an entire computer.

There are two categories of viruses: benign and malicious. Benign viruses don’t do much besides replicate themselves and exist. They may cause the occasional problem, but it is usually an unintentional side effect. Malicious viruses, on the other hand, are designed to destroy things.


Most viruses and other malicious problems are passed on through the opening and use of executable files, such as SETUP.EXE. Installing applications acquired from the Internet can also be dangerous to the health of a machine, and the growth of the Internet has made the problem of keeping viruses under wraps far more difficult than it previously was. Download and use only content direct from vendor sites or respected mirror sites, and try to get users to do the same.

In addition, one of the most common sources of viruses in recent years has been e-mail. Virus authors seem to especially enjoy writing viruses for Microsoft’s Outlook software, often using Visual Basic scripts (VBS files) to do their dirty work.

When an infected file is transferred to another computer (via disk or modem download), the process begins on the other computer. Because of the ease and speed of virus transmission in the age of the Internet, viruses can run rampant if left unchecked. For this reason, antivirus programs are crucial for every computer user’s system. They check files and programs for any program code that shouldn’t be there and either eradicate it or prevent the virus from replicating. An antivirus program is generally run in the background on a computer and examines all the file activity on that computer. When it detects a suspicious activity, it notifies the user of a potential problem and asks what to do about it. Some antivirus programs can also make intelligent decisions about what to do. The process of installing an antivirus program on a computer is known as inoculating the computer against a virus.

How to Determine Their Presence

Wouldn’t it be nice if Microsoft included an antivirus program with its operating systems? It did, but only with MS-DOS. MS-DOS comes with antivirus software that lets you detect viruses on your computer as well as clean any infected files. This software is called Microsoft Anti-Virus, and it has been included with DOS since version 6.0. The same program contains files to allow it to work with Windows.

Although Windows 9x/NT/2000/XP do not come with antivirus software, these programs are available from a number of third-party vendors. The better ones can scan for viruses in both files and e-mail and can be updated regularly from the Internet or through product updates. It is recommended that you update any virus software regularly—generally, monthly.

Know how to use install, use, and update antivirus programs, as well as how to check for viruses on a system you suspect is infected. Remember, though, that because these are third-party programs, you will not need to know specifics for the exam—just general concepts.


Because its job is to prevent programs from modifying your system’s configuration or files, antivirus software can cause problems during application installations. You should generally disable any antivirus software while installing a new application—after scanning the install files for problems, of course!

Exam Essentials

Know how the printing process works and how to troubleshoot problems.Printing is well-represented on the exam, and you should be very familiar with how print spooling, print drivers, and printer ports work.

Know how to solve configuration and corruption errors within Windows.For the test, this means being familiar with the common error messages and knowing which class of error they represent. There is only so much troubleshooting you can do in a test question, so the problems and answers are generally straightforward.

Understand viruses and virus protection.Know how to spot the signs of a virus and how to scan a system for viruses. Also know how to install antivirus software.

Review Questions


If you accidentally left a nonbootable floppy disk in a PC and then rebooted it, which error message would you be likely to see?

if the boot disk does not contain the needed startup files, as a nonbootable floppy would not, the invalid boot disk error appears.


How can a Windows 98 startup floppy be used to help fix system problems?

a windows 9x startup floppy boots to a command prompt. from there, you choose which utilities to run to troubleshoot or repair.


Which of these is a common problem involving Event Viewer?

  1. Running it creates a General Protection Fault.
  2. The Event Log becomes full.
  3. It interferes with system performance.
  4. Circular logging prevents old events from being deleted.

b.the event log can fill up. enabling circular logging allows event viewer to delete old events so that new ones can be added.


What is a VxD?

vxd files are virtual device drivers.


Which of these is not a required file for a bootable floppy?

  2. IO.SYS

a. config.sys is optional; the other three are required for booting.


Which of these steps through startup one step at a time, with user confirmation between each step?

  1. Safe Mode
  2. Safe Mode with Command Prompt
  3. Safe Mode with Networking
  4. None of the above

d.step-by-step confirmation is a separate mode from any of the safe modes.


In Windows XP, to open Task Manager, you must press Ctrl+Alt+Delete and then do what?

click the task manager button. in windows 9x, however, you do not have to do anything.


WinMSD is the name of the executable file for which common Windows utility?

system information and winmsd are the same thing.


Which type of error occurs when a program accesses memory that another program is using?

a general protection fault (gpf) is usually the result of sloppy programming, and can result from a program accessing another program s memory space or accessing a memory address that does not exist.


In which ways can a system can be infected with a virus?

viruses can enter a system in a variety of ways, including via the opening of an e-mail attachment containing a virus, by booting a floppy disk infected with a virus, or through running a program infected with a virus.



If the boot disk does not contain the needed startup files, as a nonbootable floppy would not, the Invalid Boot Disk error appears.


A Windows 9x startup floppy boots to a command prompt. From there, you choose which utilities to run to troubleshoot or repair.


B.The Event Log can fill up. Enabling circular logging allows Event Viewer to delete old events so that new ones can be added.


VxD files are virtual device drivers.


A.CONFIG.SYS is optional; the other three are required for booting.


D.Step-by-step confirmation is a separate mode from any of the Safe Modes.


Click the Task Manager button. In Windows 9x, however, you do not have to do anything.


System Information and WinMSD are the same thing.


A General Protection Fault (GPF) is usually the result of sloppy programming, and can result from a program accessing another program’s memory space or accessing a memory address that does not exist.


Viruses can enter a system in a variety of ways, including via the opening of an e-mail attachment containing a virus, by booting a floppy disk infected with a virus, or through running a program infected with a virus.

A+ Fast Pass
A+ Fast Pass
ISBN: 735608547
Year: 2002
Pages: 103 © 2008-2020.
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