Help me.... My system was running just fine until about 5 am this morning. Came downstairs to discover that my system had rebooted for some reason and I had an "invalid system disk" error. I rebooted and noted that the system HD (my WD 120 GB SE) was not recognized by the IDE controller. Played around with the cables and rebooted and it recognized but during the reboot I still got the "invalid system disk" error. Initiated a CDROM boot up with the Win XP disk and use console recovery and got back into the OS just fine. However whenever I tried to reboot using the HD only or taking out the Win XP CDROM from the CD rom drive (i.e. leaving the boot order CD, HD rather than HD first, not that it mattered), I would get an "invalid system disk error". Only when I had the CD (win xp) in the drive and had the boot order CD, HD would I be able to get into the OS. I do not have to initiate a CD rom boot (manually) or console recovery, but the CD is "search" prior to the initiation of the OS. Once in the OS everything seems OK "normal". I'm thinking that my MBR got hosed somehow. Does that make sense? Is there anything I can try short of reinstallation of the OS? Any help would be greatly appreciated. System profile below + PS Enermax 431W.