File access violation errors

I have a NT4 server and 8 nt stations. On one of them I started to get access violation errors when the user tried to run Filemaker ppro data base program. Its consistant with that user and seems to work with another user but does ocassionaly happenwith other users. This just started to happen no changes made. User has full rights to data base and apllication. Tried to reinstall the database and still failed. even tried to give the user another user ID and profile.. One other thing that does hAPPEN is when logging off or on some times get explore.exe error. asking to wait or end it.. please help Nt hs sp6a