Your PC may have too many components crammed in (multiple Hard drives?), so that with the cover on, there is insufficient cooling, the drive heats up, and the calibration is so much affected that it can't find boot tracks. Try leaving the cover on, with the PC unplugged overnight, then power it up. If it finds the hard drives then, but loses them later, you have a cooling problem. Just because there are holes to mount components, doesn't mean they system will work properly with all of the drive bays full. Fred Wagner
frwagne@longbeach.gov