Safe Mode | Microsoft Corporation Staff, IT Professional Staff - Microsoft Windows 2000 Server Operations Guide

Safe mode is a diagnostic tool for troubleshooting problems that can occur with starting and running Windows 2000. It is only accessible when the computer is started. As part of the Windows 2000 Advanced Options menu, safe mode allows the user to specifically control how the computer starts Windows 2000.

If the computer fails to startup properly, on the next restart, Windows 2000 displays the Windows 2000 Advanced Options menu, containing several startup troubleshooting options. You can also manually prompt Windows 2000 to display the Windows 2000 Advanced Options menu.

When starting Windows 2000 in safe mode, only essential drivers and system services are loaded, including the mouse, keyboard, CD-ROM and standard VGA device drivers, and the Event Log, Plug and Play, Remote Procedure Call (RPC), and the Logical Disk Manager system services. This makes safe mode useful for isolating and resolving error conditions that are caused by faulty applications, system services, and device drivers that are started automatically.

Although a computer started in safe mode has only a minimum of necessary services, you can access all partitions on functioning physical disks. Use safe mode for system startup in situations such as the following:

If Windows 2000 seems to stall for an extended period of time.
If Windows 2000 does not work correctly or has unexpected results.
If your video display does not work correctly.
If your computer suddenly slows down.
If you need to test an intermittent error condition.

Once in safe mode, you can disable or delete a system service, a device driver, or automatically started application that is preventing the computer from starting normally.

To use a safe mode option, restart your computer, and then press F8 when you see the Boot menu. The Windows 2000 Advanced Options menu appears:

Windows 2000 Advanced Options Menu

Please select an option:

    Safe Mode

    Safe Mode with Networking

    Safe Mode With Command Prompt

    Enable Boot Logging

    Enable VGA Mode

    Last Known Good Configuration

    Directory Services Restore Mode (Windows 2000 domain controllers only)

    Debugging Mode

    Boot Normally

Use   and   to move the highlight to your choice.

Press Enter to choose.

Select an option, and then press ENTER. The Boot menu is displayed again, with the words "Safe Mode" displayed in red at the bottom. Select the operating system installation that you want to start, and then press ENTER.

Important

When you select the operating system installation to start, you must choose a version of Windows 2000. Do not choose another Windows-based operating system.

When you use one of the safe mode options the environment variable Safeboot_Option is set to either Network or Minimal.

The default Microsoft VGA driver is used for display (640 x 480 x 16 colors). You must log on in all modes (either by a domain or the local SAM, depending on which safe mode option you choose).

Table 15.5 describes the Windows 2000 Advanced Options menu.

Table 15.5 Windows 2000 Advanced Options Menu

Option	Description
Safe Mode (Safeboot_Option=Minimal)	Starts Windows 2000 using basic files and drivers only, without networking. The drivers and files used are for mouse, monitor, keyboard, mass storage, base video, and default system services.
Safe Mode with Networking (Safeboot_Option= Network)	Similar to standard safe mode, but also adds essential services and drivers needed to start networking.
Safe Mode with Command Prompt (Safeboot_Option= Minimal)	Similar to standard safe mode but loads the command interpreter instead of Explorer.exe as the user shell.
Enable Boot Logging	Creates a log file, Ntbtlog.txt, during startup where the names and status of all drivers loaded into memory are recorded. The log file is stored in the %SystemRoot% folder.
Enable VGA Mode	Starts the computer in basic VGA mode in cases of corruption or incompatibility of currently installed video driver. The basic video driver is always used when you start Windows 2000 in any kind of safe mode.
Last Known Good Configuration	Starts Windows 2000 using the settings (registry information) that Windows saved at the last shutdown. Use Last Known Good Configuration only in cases of incorrect configuration. It does not solve problems caused by corrupted or missing drivers or files. All system setting changes made after the last successful startup are lost.
Directory Service Restore Mode	Allows restores of Active Directory on a domain controller. This option is not available on computers that are running Windows 2000 Professional or on member servers.
Debugging Mode	Starts Windows 2000 in kernel debug mode, which allows a debugger to access the kernel for troubleshooting and system analysis.
Boot Normally	Starts Windows 2000, loading all normal startup files and registry values.

If you are using, or have used, Remote Install Services to install Windows 2000 on your computer, the advanced startup options might include options related to restoring or recovering your system using Remote Install Services, in addition to the options described above.

If you plan to start the computer in safe mode and then use Backup with Removable Storage, the only safe mode options you can use are Enable VGA Mode, Last Known Good Configuration, and Directory Services Restore Mode.

When the computer is started with any of the safe mode options except Last Known Good Configuration, a boot log of devices and services that are loading is created. The log is saved to the file Ntbtlog.txt in the folder in which Windows 2000 is installed (typically \Winnt).

If the problem was caused by a newly-installed driver, you might be able to start the computer using the Last Known Good Configuration option so you can research the problem with the driver. If there were other causes, after starting the computer in safe mode, you can use Event Viewer, System Information, Control Panel, Backup, and other tools to try to diagnose and correct the problem.