System File Checker Problem

I am running Windows 2000 on a Dell. When I check the event log, I am getting the following message for what appears to be EVERY file in the System32 directory: File replacement was attempted on the protected system file “flename.exe”. The file was restored to the original version”. The version of the system file and the “bad” file is identical.
Any idea what is causing this event? I recently did a non-destructive upgrade to Windows 2000 from the Dell recovery CD. This did not resolve the issue.