Lockup when switching users or logging out

[SnowBall]

Hi,
I'm running a DELL Dimension 4100 PIII 733 with XP SP 2, 40 MG harddrive. Installed the XP back in about 50 days ago. Now it locks up whenever I try to log out or switch users. No firewall installed (XP firewall running), Norton's Anti virus 2002, Outlook Express 6, using dialup for internet. I found the following in the event viewer. It seems to coincide with everytime I have to cold reboot:

Event Type: Information
Event Source: dcfssvc
Event Category: None
Event ID: 105
Date: 31/01/2004
Time: 5:42:47 PM
User: N/A
Computer: CLIFF
Description:
The description for Event ID ( 105 ) in Source ( dcfssvc ) cannot be found. The local computer may not have the necessary registry information or message DLL files to display messages from a remote computer. You may be able to use the /AUXSOURCE= flag to retrieve this description; see Help and Support for details. The following information is part of the event: .

Oh yeah .. forgot .. I use this on a home network with one other computer running Win98. (No problems with that one (-: ))