I would check the BIOS settings and see if they got changed somehow. If you drive requires a
manual setting and it got changed to auto, this could cause your problem. I remeber having a
similar issue a few years ago and the drive was at the end of its life. No matter how I changed the
BIOS, it would work for a seesion and at re-boot, the problem would reoccur. Finally, the
drive gave out.