Blank Screen with mouse cursor !!!

I have a NT 4 domain running about 170 machines. The workstations OS’s is Win2k and Win98. I run a logon script mapping a few drives, installing and updating Trend AntiVirus. On my Win2k machines I get a blank screen with a mouse cursor and that is it. This only happens on random machines and ONLY on the users account, NEVER the admin account. I run a different logon script for administrator. I have tried changing the logon script for the users to have the minimum requirements running, but it still doesn’t work. WHAT DO I DO?