I was in the middle of working with MS Word on Sunday when my computer started to make a loud whining sound. It then froze for a few minutes, the screen starting making these odd waving ripples, and then the computer shut down. When it tried to start up again, it said "error could not load OS" (or something to that effect). I tried hitting the restart button, but the error message popped up again. I then shut down the surge protector and restarted, and everything was fine. I was just sitting at my computer (Friday), and it started to whine and froze once again. However, it did not shut down, and unfroze after about one minute. I have heard this whining noise in the past, but it was always at night while I was going to sleep, not on the computer (i.e. there was no computer activity), so I never realized that there was anything to be worried about. Is my power supply going, or does the fan just need a good cleaning, and is there any diagnostic software that will let me know?