I just came downstairs to find that my fan on my dual 2 Ghz G5 was spinning full blast. The screen was asleep so I tried moving the mouse to "wake" it. Nothing happened and I had to force shut down the computer by holding down the power button. When I restarted the computer the GPU, which is an X800 XT that purchased a few months after I got the computer, was making a weird humming and rattling noise. It has only now just settled down (about 10 min. after the event). Is there any cause for alarm, or is it just perhaps a glitch of some sort?