"Inaccessible boot device" error when you start Windows 7 or Vista after changing the SATA mode

If you change the SATA mode of one of your hard drives in the BIOS, so it will use the AHCI specification, you might find that after you restart the computer you get an error message that says "inaccessible boot device." That happens if the drive you changed was your boot drive and the AHCI driver is disabled. You need to enable this driver before you make the BIOS change. To find out how to resolve the issue, see KB article 922976 at Click Here