Nt Workstation “hangs” on shutdown

I have a NT workstation running SP 6 and on NTFS that 9 out of 10 times “hangs” on shutdown and restart. It doesn’t matter who is logged into the machine. After you select to shutdown it gets to the “Please wait while the system saves to disk (etc)” and then it locks up. There is no log about this in Event Viewer and it doesn’t seem to matter how much network activity occurs on the PC before this happens. Does anyone have any ideas before I format the lot and reinstall NT?