sconstantine ... I read your response and was initially excited and tried your solution, but of all the updates you listed only one was on this workstation and removing it did not work..
I do not have the luxury of re-installing windows or recoverying windows xp everytime, because I work for a school system and this nasty c000021a stop error is now on 21 desktops and laptops and counting. Some of them had the windows updates turned on, and others did not. Some are dell workstation, some are dell laptops, other are gateway desktops and gateway laptops. The model numbers are numerous. needless to say that this is not happening to any one specific machine type. I have tried all the microsoft (so called knowledge base) help files, which there are several addressing this specific issue. They range from alleged issues with IE to removing these updates as you suggested.
I have also tried booting into safe mode, but everytime the machines stops then auto reboot after trying to load AGPCPQ.sys. So my genius solution was to use recovery console to stop loading this AGPCPQ.sys at boot, but when I try to restart in safe mode again it now stops at AGP440.sys. Yes! I stopped that one from loading as well, but now it stops at mup.sys. Obviously this is not the solution.
Dell, Microsoft and Novell were all consulted, and as you would expect and bunch garbage and no solution.
Any suggestion will be greatly appreciated.