All the drivers that are included with Windows XP use digital signatures to verify that they have been tested by the Windows Hardware Quality Labs (WHQL). Many third-party programs are written for Windows XP must install additional drivers that have not been tested by WHQL. Therefore, they do not receive a digital signature.
Note Some third-party vendors have tools that they can use to generate a valid digital signature even if these products were not tested by WHQL. The following procedure cannot be used to determine whether these drivers are installed.
Windows XP includes the File Signature Verification tool (Sigverif.exe). You can use this tool to find all files on your computer that are not digitally signed. For the purposes of Windows XP clean-boot troubleshooting, you have to test only the files in the %Windir%\System32\Drivers folder.
To use the Sigverif.exe tool, follow these steps:
1. Click Start, click Run, type sigverif in the Open box, and then click OK.
2. Click Advanced, click Look for other files that are not digitally signed, click Browse, locate the Windows\System32\Drivers folder, and then click OK two times.
3. Click Start.
After Sigverif.exe is completed, a list of all unsigned drivers that are installed on your computer appears. Above given tips if creating any problems to unsigned driver contact to operating system support technician
