You can use the Windows XP Signature Verification tool (Sigverif.exe) to find unsigned drivers and verify device drivers in Windows XP. This can be helpful for troubleshooting system instability, error messages, boot problems, and so on.
Verify Unsigned Device Drivers
1. Click Start--> click Run--> type sigverif, and then click OK.
2. Click Advanced.
3. Click Look for other files that are not digitally signed.
4. In the Look in this folder box--> type x:\Windows\system32\drivers--> where x is the letter of the drive where Windows XP is installed.
5. On the Logging tab--> make sure the Save the file signature verification results to a log file check box is selected--> and then click OK.
6. Click Start.
NOTE: The log file is named Sigverif.txt, and it is saved in the Windows folder. Third-party drivers that are unsigned are displayed as "Not signed." Use the drivers in this list as your troubleshooting starting point.
Disable Unsigned Device Drivers
A common problem is power management features, and Microsoft requires power management support to certify drivers. Many third-party unsigned drivers lack this support, resulting in power management problems (such as problems going into or coming out of hibernation and standby).
After you find unsigned drivers, you can disable them by using any of the following methods:
1. Disable the device in Device Manager (you may have to click Show hidden devices on the View menu, and then disable the device under the Non-Plug and Play Drivers branch).
2. Uninstall the software that installed the third-party driver by using the Add/Remove Programs tool in Control Panel.
3. Rename the driver in the Winnt\System32\Drivers folder.