I hope you've backed up your data recently. This sounds like the experience of an IT manager - a pro - who recounted his experience in ComputerWorld (see here).
As it turns out, this malware went really deep. Not only did it infect Windows, but it also inserted itself into Safe Mode. Usually, we can boot into Safe Mode to run a virus scan, but not this time. In fact, I discovered that the malware actually got into my system BIOS. That's right, it went so deep it actually got into my hardware. Even a BIOS upgrade didn't get rid of it.
In the end, I had to disconnect my CMOS battery for a day to clear the BIOS, completely reinstall Windows and restore from backup.
Your problem may not be exactly the same, but it sounds like it.
If the above advice doesn't help you, you may need to find someone to repair the PC (it really could be an unrelated hardware problem). Not being able to boot up does restrict the options available.
One thing though : what make and model is this, and is it Win7 SP1 or SP2? I can check some of the specialist hardware forums for similar problems. Unlikely to find an answer, but you never know.Message was edited by: Hayton - poster already said it's Win7 - on 09/09/12 00:44:05 IST
Some Avs Mcafee included supply when ased a cdrom based scanner. Unsure if cleanboot Mcafee's version detects this beast but could be a thought.
@alexander2012 : promotion of other Anti-Virus companies' products is not allowed unless a poster can demonstrate clearly that a rival product offers some feature that McAfee does not, or is currently detecting and dealing with a threat that McAfee has yet to include in its database. You did neither. I've removed another of your posts and a third post is under review.