Real quick... I have a neighbor whose HP Pavilian has been making a buzzing sound even after the computer has shut off. I have isolated the noise to the processor fan, which seems to be missing a fan blade... I haven't yet been able to determine if the blade is still in the fan somewhere or not, but I'm doubting it. The primary issue to me is why are the fans staying on indefinitely after the computer itself has been shut off. Once unplugged it obviously quits, but as soon as it plugged back in, the fans turn back on. Any hints?