A component may be overheating. Could be the power supply. Most cpus won't cause problems until they're almost fried, causing windows bluescreens. If you want to reinstall the cpu, you can ground yourself against metal first to get rid of static discharge from your hand, then unlock the heatsink and twist it gently sideways before you lift it off. Then open the cpu lock down lever and lift it out. Gently wipe the cpu with rubbing alcohol or fingernail polish remover (acetone). After cleaning both the cpu and heatsink, apply a single drop of thermal paste on the heatsink only. Spread it around with a single edge razor blade or old credit card for a thin even layer. If you can see it on the surface, you have enough. Then reinstall in the reverse order and lock both the cpu and heatsink down, or press evenly for a socket 775 heatsink to engage each corner. Your most likely culprit is either the ps or video card temp.