All of a sudden, all the users in my organization can't permanently delete files from their own folders on the server. After a user deletes a file from a folder, the next time he or she logs on to the server and opens the folder, the file reappears. I can delete the files directly on the server, but doing so isn't a permanent solution. I've checked all the users' permissions, and the users have full control of their own files. I haven't made any changes on the server or to the user folders. Could a virus be the cause? I've kept my antivirus software up-to-date, and scans haven't turned up anything.

I'm sure that Windows 2000 is the cause of your problem. Win2K's synchronization algorithm checks every file and folder in a roaming profile to see whether it exists in the local profile. When Win2K discovers that a file or folder is missing, the OS propagates the file or folder to the appropriate destination. To my knowledge, Microsoft hasn't corrected the algorithm in any service pack. The only remedy I can suggest is to avoid using roaming profiles, but this workaround probably won't work for you.