System Lock up on advanced graphic programs

I have been having this problem for about a month now and I'm going crazy! It started out in a game Unreal Tournament 2004 when after about 10 minutes I would get total lock up, could not exit, no keys work, Ctrl, Alt, Del did not work nothing had to do a hard reboot, when I checked event viewer there was no log in application or system. Well I just thought it was the game but now it's happening in other apps. I do a lot of digital art like Bryce5, Terragen, Mojoworld etc, and in the middle of rendering a scene I get total lock up again! Well I did a benchmark on my Display adaptor and it gave me an error msg that my
driver ati2dvag got stuck in an infinite loop stating that there was a problem in the device itself or the driver. Well I went ATI site an found the error message "stuck in an infinite loop" and they say it's in the B.I.O.S.? All these programs ran fine before, checked for spyware, virruses, I defrag the hard drive, did a chkdsk. nothing is there!! Could someone please help or give me some clues before I do a reformat! My system is Athlon2100+, 1280mb ram, Kt266 Chipset ddr ATX, 80 gb HD, ATI Radeon 7000 64mb SDR graphics card Running XP home edition.
Thanks for any help!!!!

 

Forgot to mention that about the same Time this started happening I installed Zone Alarm Firewall, Then read that other people had nightmares similar to me with lock ups and blue screens etc. Well I uninstall ZA and am now using Sygate. Got rid of all ZA files I think? Looked in reg and did search foud just 2 small ones and got rid of them. Could ZA altered somthing in my system causing this problem? Thanks again

 

According to one of thier solutions (on the Ati site) try turning off "fast writes".. This can be found in the Ati control panel in the display properties.

Control Panel > Display > Settings > Advanced > SmartGART

 

Can't find anything that says "fast Writes" closest thing I see is a box that says Enable write combinig and it is checked

 

Ok someone else suggested that it was heat related so I poped the side of my box off and stuck a big fan in there and got 2 of the programs to run stable. Still locks up on UT2004 Though Appreciate the advice and suggestions, Still trying other stuff so please give me some more advice
Thanks again!!

 

what about trying newer or older Ati drivers? Or maybe UT2K3 patches...

http://downloads.guru3d.com/

 

Also check you motherboard mfg websute for possible driver updates.