Right here goes, went to boot up my pc only for it to say it could not detect any drives. I have 2 seagates a 250GB and a 500Gb, the 500GB had the os/files on it and the 250 just had some movies etc. I removed the 250GB drive and tried to boot it up and still got the same problem, did the the same with the 500Gb and still wouldn't boot. I then formatted the 250GB drive and installed windows xp on it, installation went fine so I shut it down and went to put the 500GB back in. After I put it in and went in to the bios to make sure it was being detected I seen it said drive unknown and also said the 250GB drive was "unknown". Again it failed to boot so I disconnected the 500Gb and went in to the bios, this time the 250Gb showed up fine in it and also booted no problem but anytime the 500Gb is attached the pc refuses to boot, even when I have it turned off in the bios. Anyone have any ideas? Both drives are seagates and there sata.