I was really stuck with this problem. My desktop just shut down during use reporting the problem. Nothing I did would get it to restart from the hard drive. In the Bios it had slipped to 3rd place in the boot list, but each time I reset it, it again failed. It had been working with out problem for 2 years or more. It seemed as if it never got to try booting from the hard drive. I read this report on my secondary computer so decided to try. Reseating the hard drive that is. It worked first time. Thank you very much.