Could be your Hard Drive yes, Im not sure as Im not too familiar with Hardisk crashes. Though Im most certian that if your HD died you wouldnt boot up at all.
Anyway your programs wont start up this could either be A: A system error or B: A faulty hardware.
Since you still can log in to windows that means that your hardware is still intact though there may be some major issues with your hardware that make your computer crash. Though nothing is completely destroyed yet...if it was so it wouldnt boot up at all.
This sounds more like an overheating issue, either in your chassis or your processor. May I ask what motherboard you have? Is it AMD or Pentium?
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