Cannot do Run unattend repair of XP

I have a Compaq computer. When I try to do a, Run C:\I386\winnt32.exe /unattend, repair I get the following:

Windows XP Upgrade Compatibility
Setup cannot upgrade due to third-party kernel.
Windows has detected that one or more protected core system files (kernel) on your computer have been modified. The Service Pack contains updated versions of those files, which work to provide a stable environment for your programs. Due to this modification, the Service Pack will not be installed. For more information, see Knowledge Base article Q327516 at http://support.microsoft.com.

When I go to microsoft, it cannot find Q327516. I would like to fix this without a format and reinstall.

 

Thanks PeteC, you saved me many hours. Q327101 is not the number recieved. It was Q327516. Step 5 was the one that saved me. I did not have BootXP or LogonUI Boot Randomizer. I was unable to boot directly
to the desktop and had to "jump thru hoops" to get there. After step 5 I can go to the desktop and do a repair. Thanks again!