System File Tools

Windows XP Professional provides tools to help you troubleshoot problems caused by incompatible, missing, or corrupted driver and system files. Helpful tools for troubleshooting system and driver file issues are listed alphabetically in Table D-15. These tools enable you to detect and correct issues caused by problem files, or prevent their installation.

Table D-15: System File and Driver Tools

Tool	Function	Tool Type, Interface
Driver Query (Driverquery.exe)	Listing information about the drivers on a computer.	Built-in, command-line
Driver Signing and Digital Signatures	Maintaining system stability by verifying that device drivers have passed a series of rigorous tests administered by the Windows Hardware Quality Labs (WHQL).	Built-in, GUI
Windows File Protection	Scanning protected system files and restoring overwritten files with the correct versions provided by Microsoft.	Built-in, GUI

Driver Signing and Digital Signatures

Driver signing is a multistage process in which device drivers are verified. For a driver to earn this certification, it must pass a series of compatibility tests administered by the Windows Hardware Quality Labs (WHQL). Due to stringent WHQL standards, using signed drivers typically result in a more stable system. Microsoft digitally signs drivers that pass the WHQL tests and Windows XP Professional performs signature detection for signed device categories, such as the following:

• Keyboards

• Hard disk controllers

• Modems

• Mouse devices

• Multimedia devices

• Network adapters

• Printers

• SCSI adapters

• Smart card readers

• Video adapters

A Microsoft Corporation digital signature indicates that a driver file is an original, unaltered system file that Microsoft has approved for use with Windows XP Professional.

Windows XP Professional can warn or prevent users from installing unsigned drivers. If a driver is not digitally signed, the user receives a message that requests confirmation to continue.

Microsoft digitally signs all drivers included with the Windows XP Professional operating system CD. When downloading updated drivers from a manufacturer s Web page, always select drivers that are signed by Microsoft.

Windows XP Professional provides the following tools to help you identify digitally signed files:

• File Signature Verification

• Driver Signature Checking

• System Information

• Device Manager

• DirectX Diagnostic Tool

• Hardware Compatibility List

File Signature Verification

The File Signature Verification tool (Sigverif.exe) detects signed files and allows you to do the following:

• View the certificates of signed files to verify that the file has not been tampered with after being digitally signed.

• Search for signed files in a specific location.

• Search for unsigned files in a specific location.

To run File Signature Verification

• In the Run dialog box, type sigverif.

When you click the Advanced button, the Advanced File Signature Verification Settings dialog box provides additional configuration options on the Search and Logging tabs.

Search

You can specify file search options such as whether to search all drivers or limit the scope of your search by using file name and folder criteria.

Logging

You can specify that search results be saved to a file, the log file name to use, and whether to overwrite or append the log file. You can also view the log file by clicking View Log.

File Signature Verification writes information to systemroot\Sigverif.txt, a log that contains the following information about the scanned files:

• Name

• Modification date

• Version number

• Signed status

• Location (name of catalog file)

Driver Signature Checking

Driver Signature Checking enables you detect unsigned drivers before you install them. Using Control Panel, you can set verification levels for driver signature checking to ensure that Windows XP Professional inspects files for digital signatures whenever you install or update drivers.

To enable Driver Signature Checking

1. In Control Panel, open System.

2. Click the Hardware tab, and then click Driver Signing.

Table D-16 describes the three levels of file signature verification that appear in the Driver Signing Options box.

Table D-16: Signature Checking Levels

Level	Description
Level 0 (Ignore)	Disables digital signature checking. The message that identifies a digitally signed driver does not appear, and all drivers are installed even if they are unsigned.
Level 1 (Warn)	Determines whether the driver has passed WHQL testing. A message appears whenever a user tries to install a driver that fails the signature check.
Level 2 (Block)	Blocks installation of a driver that fails the signature check. You are notified that Windows XP Professional cannot install the unsigned driver.