Hi ssummers, and welcome to BleepingComputer.
Have you opened the case and cleaned it out? There are electronics inside the case that are very susceptible to electrostatic discharges, to protect your computer, touch the metal of the case to discharge yourself of any charges your body may have stored before touching any of the components inside. As a safety precaution you should unplug the computer to avoid electrical shock.
The most critical place to keep clean is the heat sink and fan on the CPU, if dust accumulates there it can cause thermal shutdowns. If you take a pencil and place it inside the fan it will it will keep the fan blades from spinning while you blow out the fan and heat sink.
Edited by dc3, 19 June 2008 - 04:54 AM.