I have an old small computer, and in recent days it has been abnormally loud, as tho fan bearings are gone? But today, to my surpise, it has quieted right down, and is so quiet, I'm starting to think a fan has actually stopped running. If so, any ideas on how much operation might I expect from it before it overheats dangerously? It is a 3 gig computer, circa 1997, using Windows 98. The case doesn't feel unusually warm, and all my functions are performing normally. I have backed up all files, and apart from hassle, can afford to replace this computer, I'm just curious, what could be going on?