are there loose cables connecting it to the motherboard? is there pounds of dust inside your case causing errors? I would open up the case and see how all the parts are doing, and if need be, with the power disconnected from the wall of course, vacuum out the dust from everywhere and make sure all cables are secure.
removing the clumps of dust by hand first, and then using a can of compresed air to blow out the dust is the best method. Be sure not to blow the fans on video cards or otherwise unless they are disconnected because there's a chance you could backfeed current and blow the circuit it's connected to. Also, don't use a vacuum with a metal hose, use a plastic tip and always keep one hand on the frame of the chassis to be sure you ground yourself to it.