SP3 cannot be installed

"The upgrade patch cannot be installed by the Windows Installer service because the program to be upgraded may be missing, or the upgrade patch may update a different version of the program. Verify that the program to be upgraded exists on your computer and that you have the correct upgrade patch." Other than SP3, almost all other updates installed just fine. Thanks

Tom, please don't post the same problem in more than one thread. I answered in your other one.