Run time error ’53’

I am running an Access 2000 database. Everything runs fine on all machines except a Windows 98 machine. This occurs after logging on to the database. An error pops up: Run time error ’53’ The error gives 3 choices, End, Debug , and Help None of the choices does anything. We cannot end Access. A reboot is all that we can do. Do you have any ideas as to why this is happening?