Critical Error message

[Chaos4All]

First off let me give you a list of my current computer hardware...

Custom EnPower Gamer from PC Club

Radeon 9600xt Sapphire videographics card
Athlon 32 OS running Windows XP home edition
80-gig hard drive
1024 gig ddr-400 RAM
48x CD Drive
Modern CRT monitor

The Problem:

When playing Dawn of War:WA, mainly after a large game or a couple of small games, it will shut down the game, return to windows. There it shows a window that says "Program has encountered a serious error and must close". If I restart it will happen again sooner than before, but if I shut it(computer) off for an hour or so it will work fine for a while.
Sometimes, during play, my computer reboots itself, and when it is back on, says "Radeon 9600xt has encountered a critical failure and was forced to reset".
I think it is overheating, but I have three case fans, the power supply fan, and a fan on my graphics card. I have recently dusted it with spray-air,too. I defragmented my hard drive and uninstalled other large programs.. It has never been on-line(no point at 28.8 kbps dial up I have now) so no viruses. It was updated about 8 months ago to run Doom 3 better.
Any ideas? I have to use it for another few months until I upgrade to a better system.

I will post notifications as tips come in, and will keep trying to fix it on this end.

Thanks

[ZellFish]

A: Update your graphics drivers. See if that solved the problem, if not, post the results here.
B: Save the PC upgrade to pay for a couple months of Broadband..
C: How old is your computer?

[TBS]

Overheating is a distinct possibility, all I can suggest is that you take the side off your case and point a fan in there and see if things improve - if they do then you will need to look at a more long term cooling solution.

THe other possibility is bad RAM - download memtest86 (google it) and use it to check your memory.

Moving this thread to the DoW tech help forum.

[Chaos4All]

Thanks i'll try the tips and post results. The computer and all hardware will be 4 years old in december.

[Chaos4All]

Well, I've checked into overheating...no proplems
Updated to newest ATI Catalyst driver...Went from crashing after ten+ minutes to crashing after less than five.
I have done everything....Turned VPA(?)recovery, lowered detail settings, etc.

Memory is not the problem, as diagnosing tools found no errors, and my computer recognises both 512 cards.

Ive seen other threads about ATI cards malfunctioning during DoW, any connection?
Please Help!