Pull the hard drive out of your laptop and hook it up to a desktop that is working fine. You will probably need a converter to go from the larger IDE cable to laptop size, it shouldn't run you more than 15 dollars at a computer store, or just get it off newegg. Next, open you hard drive, and back up everything you want. Then, just do a clean install on the laptop hard drive, you'll spend way more time trying to figure out the problem then just reinstalling everything. Obviously, this will not work if you are having a hardware problem, but at least you will know it is a hardware problem if it doesn't work.

<-- It was Lebron, in the Palace, with the fadeaway