I'm not sure what's happening but I have a feeling it's either Win 7 or a hard drive about to fail. Starting this morning I had a lock up of my PC which I then had to turn off the power to the PC and then restart it. I started getting the "reboot and select proper boot device" prompt which with past computers has meant a hard drive was dying. I'll power it off again and it'll boot normally into Win 7. I will leave my PC on and then after 20+ minutes, it will reset and the prompt will come up again. Now my main concern is that I don't know which HD could be failing. I have a 120 GB SSD as well as 1 TB HD.
My specs as follow:
Win 7 64 bit Pro
i3 760 2.8 Ghz
120gb OCZ SSD
1 GB WD HD
ATI 5870 1 GB
might Google your motherboard looking to see if the SATA controller has had problems. I had a biostar they built with a batch of bad SATA controllers that would start to fail after a year or two. same intermittent problems.
So the SSD was faulty. Had some diagnostics run on it by an IT friend and something with putting my computer to sleep instead of shutting it down completely every night caused the drive to simply run out. I ended up buying an intel 320 series 80gb SSD to replace it.