I am having the same problem. All of a sudden, one day my computer wanted a login, and nothing I could remember worked. I did a hard shutdown, and now I get nothing. When I press the power button, only my case fans come on, but no boot attempt or HD activity. I have done some research here, and realized this may be a BIOS issue. I changed to option to allow overclocking, but didn't change the speed. I am going to reset my BIOS tonight and will report back.