Nt4.0 Server User32.Dll error

I am working on a small network where the PDC is worked on as a workstation also. We recieve an error that User32.dll will not initialize and causes everyprogram to fail to start. I have attempted to overwrite the .dll, repair the .dll and now Doing a full backup of the server in hope that I can overwrite the user32.dll on the backup tape and not cause an error. Anyone have a good idea? My last thought is to reinstall NT4.0 Server.