I just had this same problem and figured it out after some trial and error. What I did was make a bootable flash drive using Power ISO with an ISO dump of Windows 7 on it. I then went into the bios and changed the boot sequence to boot to USB drive first. At first this did not work and I could not figure out why so I tried a different USB port on the PC and wallah! It worked. I was able to restore the OS after formatting the hard disk. (Not sure if formatting is necessary or not.) I hope this helps someone.