When you attempt to install SP1 on Windows XP, you receive a message similar to:

one or more protected files on your computer have been modified.

You will receive this message if you have a modified version of Ntoskrnl.exe, usually provided by 3rd parties to display customized graphics when your computer starts up.

Service Pack 1 contains an updated version of Ntoskrnl.exe, which must be installed with the service pack.

The following programs will cause this condition, but others may exist:

LogonUI Boot Randomizer

If the installer offers to replace the file, respond OK. After the service pack is installed, or if the installer quits:

1. Use Control Panel / Add/Remove Programs to uninstall the 3rd party application.

2. Open a CMD prompt and type:

attrib -r -s -h c:\boot.ini

3. Open c:\boot.ini in Notepad and remove any /KERNEL= switch that may be present.

4. Restart your computer.

5. If the service pack did NOT install, try installing it now.