STOP error on during shutdown

When shutting down my computer, after seeing "Please Wait .... Windows is shutting down" goes away, I just see a blue window/screen. After about 5-10 minutes, I see the following message: "STOP: C000021a {Fatal System Error} The Windows Logon Process system process terminated unexpectedly with a status of 0XC0000005 (0X00000000 0X00000000). The system has been shutdown". I then just power it off by holding the down the power button.

I have searched on this error and have come across it many times, but it mostly deals when someone is trying to logon. I have run Ad-Aware SE, Spybot - Search & Destroy & CCleaner. Right before I first started seeing this, I remember IE acting kind of strange. When I would click on the drop down box in the Address field, it would hang for a few seconds then continue. I recall experiencing this same thing a while back & I think I ended up changing the permissions of a security file somewhere. But I can't remember what file/folder or where. Does this sound familiar with anyone?

I've also tried F8 - Last known good configuration. Also don't see anything specific in Event Viewer.

Dell Latitude D600
XP SP2
IE 6.0.2900.2180 SP2

Thanks in advance,
Mike