Windows 98 won’t shutdown

I have Windows 98 as clients in an NT domain.Users are having problems shutting down their pc.When they click start and choose shutdown,the system will close all programs as if it’s shutting down but the system will freeze to the screen Windows is Shutting Down.Even if you left it overnight users can still see the same screen when they arrived the next day.Can you pls help me on this. Thank you.