Compaq Computer

Compaq Computer began to automatically stop any time. What should I do to solve the problem?
My Compaq FS7600 is only 1 1 / 2 years and problems have occurred. The blow-PC automatically shut down anytime to play a game or enter in the internets. Halfway to play game, then the blow-off PC. Another problem, I have to wait about 30 minutes to restart my computer. It takes about 2-3 minutes to the office to open and another 5-8 minutes to open MSN or Yahoo on the Internet. I deleted all unnecessary documents, music, and no disk cleanup and defrag your PC, but still kick-off automatically. Can someone guide me on how to correct these problems? Thanks in advance
replace power supply, which should solve the problem … if it was an overheating problem CPU, wouldnt off, but simply freezing
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