I think you need to address that hard drive issue first.
The first thing to do would be to run a hard disk diagnostic program. If you know the brand of hard disk you could get the diagnostic program made for their disks, but that will be difficult if you do not have a working Windows 7. If you are comfortable inside a computer case you could remove the hard drive and read the brand off of it.
However I have found that this Hitachi "Drive Fitness Test" diagnostic disk works on most hard drives regardless of brand:
Downloads . You download the ISO file, burn it to a CD, and then boot with the CD and the test will run.
Before you run that you want to check that the cable connections to the hard drive and the motherboard are not loose. Do this by simply unplugging them and re-plugging them to be sure they click all the way in. Use proper anti-static procedures inside your case.
Then run the test and tell us what the result is.