My Logitech Revue's fan has suddenly begun to run constantly whenever it's plugged in (even when not using it). I opened it up and blew out all the dust with compressed air in case it was keeping the heat sink from cooling, but there really wasn't that much in there. Is this maybe a software problem that it's not getting the message that it has cooled so it continues to run? The fan seems to work fine, but it's a bit noisy when it runs all the time.