Quote from hailgodmc
Its a laptop right? do you move it around much while its on? might have caused physical damage to the disk.
I rarely ever move it since it stands as a replacement to my desktop which is currently not functional. The few times I do I always shut off the computer and put it in a fairly solid bag. I've treated all my other laptops far rougher than this one (all of which are fairly old by now) and none have had any issues at all.