Is there a clicking noise coming from the harddrive? If so, this is called the "Click of Death" and quite often leads to the failure of your drive.
The Click of Death repeats over and over...not just like three times and thats it...it sounds sort of like the drive spinnig up, but doesn't stop after a few seconds.
I'm guessing there's some other problem with your drive, though.
i have the same symptom with my Latitude and Sololol, was planning on buying new HD's soon..
Well, you better back up your data...