Inform windows, system specs, check if video card is not dead, give full Diagnostic Report about your video card,
Inform your power supply
What version of 7600Gs you're talking about?
There is 128MB and 256MB.
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Aside from reinstalling the drivers I'd say its likely a hardware error, and I'm guessing its probably either the power supply or general incompatability between the 7600GS and your system, I'd honestly sugest to check if video card is compatible with your motherboard, I'd sugest also a bad thing, buy a new video card or change it to a newer,
7600GS is problematic among new drivers, check correctly if these drivers really matches with your video card, there may be a problem between you are installing drivers for 4000 to 6000 series for example, this probably may be the cause.