Infrequently my desktop will freeze up. Sometimes I can restart it no problem, but every once in a while I will have to do a hard shutdown and on reboot if I check the bios the hard drive is not recognized. I remove the hard drive, use another computer to run WDlifeguard on it, and when I put it back in the same computer it works great again - for a while. I have had a WD 620GB hard drive, a Hitachi 500GB hard drive and a WD Caviar Blue 500GB HD installed with the biostar GF7100P M7S motherboard. The 620GB and the Hitachi have both been working in other computers for over a year now since I took them out. I can hook another HD to the motherboard and it is recognized immediately. I can move the HD to another computer and the HD spins up immediately. But after about 6 to 8 weeks this desktop has a fit and won't recognize the HD. Anybody got any idea's?