Computer Just shuts down.......

[Superior Beatslayer]

I don't think that the problem is Doom 3, just aint logical, so I think it may be because my computer gets too hot, when I checked its temperature in the BIOS it was 55 C, I hear it could be my power supply as well.

[Suicides-by-Steve]

That's not too hot. Remove your Graphic Card, reboot- and install the new drivers. Corrupted, or misinstalled graphic drivers can cause the problem that you describe- it may not be the cause, but it's one of the easiest steps you can perform to troubleshoot. My inlaws had the exact same problem. Make sure that you use an uninstaller to remove all traces of the previous driver.

If you suspect that it's your power supply, make sure you check your power options... the cause may be hidden there as well. Make sure that you're comp isn't set to go into Suspend Mode or some such setting.

[Superior Beatslayer]

That's not too hot. Remove your Graphic Card, reboot- and install the new drivers. Corrupted, or misinstalled graphic drivers can cause the problem that you describe- it may not be the cause, but it's one of the easiest steps you can perform to troubleshoot. My inlaws had the exact same problem. Make sure that you use an uninstaller to remove all traces of the previous driver.

If you suspect that it's your power supply, make sure you check your power options... the cause may be hidden there as well. Make sure that you're comp isn't set to go into Suspend Mode or some such setting.

Suspend Mode? thats the first time I have heard of this, although I can get the jist of what it does, how do I switch it?

[Suicides-by-Steve]

Control Panel-> Performance and Maitenance-> Power Options. Look around in there for anything that looks like it may be the root cause. Generally, the comp going into Suspend Mode shouldn't happen during CPU usage- but you never know.

You may also want to physically remove and plug back in your Graphic Card, and while you're at it- check to make sure all other things are plugged in properly.