I wouldn't think that it is a hardware issue, although I'd suggest getting a faster cpu, but more likely software. I'd try reinstalling Doom first and then get the latest ATI drivers. If that doesn't work, look up Doom 3 troubleshooting and see if you can find a similar problem and a fix for it. If it still fails to play, you might have a hardware problem, but I can't see it just affecting Doom 3 if you do. Does your computer crash like this in other programs?

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