One possibility: you're using a guest account (in a Windows NT based OS, such as 2000 or XP). If you remove some extra desktop icons, they come back each time you log in.
Another possibility: Windows 2000 has some sort of System File Protection. In other words, even if you delete winword.exe, and empty the recycle bin, the system can still bring it back.
A third possibility: If their systems aren't secure, to the point that you can royally fvck something up by deleting some critical system files, they may just be popping in a restore CD created from Norton Ghost or some other program like that, to generate a "fresh" and ready installation in well under an hour.