Windows XP File Protection?



Just recently, I will occasionally receive a pop-up warning message from Windows stating that some key files were replaced and that I should insert my XP Professional CD and restore the files to their original state. However, these messages appear randomly (that is, they don't appear after an application install or system change) and are annoying because I've "restored" the files many times only to have the dialog box reappear later. I'm scared not to restore the files as Windows threatens me with system instability if I ignore the warning. Any clue?
Have you changed any files like shell32.dll, your start button..anything like that?

if you haven't and are still getting those messages scan for viruses...after you've done that goto your command prompt and type in

sfc /scannow

if you have changed any of those files I mentioned or such just cancel and windows will learn to cope and everything will be fine :)