I've been trying to fix this issue for a while. The original problem was "operating system not found". I ran tests on the HDD for bad sectors but there were none. I saved the data and reformatted the HDD. I was having an issue with Windows installation not picking up the drive.
Finally I created an ISO to USB and I was able to install the OS (Vista) on the machine. Now the BIOS will intermittently detect the HDD and the DVD Drive. I can go in and change the BIOS setting to default and I can get it to boot but when I shutdown or restart it give the error message "operating system not found" again.
Has anyone seen this before? Is it a bad mobo (controller)? Thanks for any input on this issue!