test the drive with the mfg specific tools. that will tell you for sure if the drive is bad or not. you may need to let the test run for a few hours.
if the drive turns out to be faulty, get all or as much data as you can transferred to an external drive or something. this is probably a good idea anyway. anything you dont want to lose. replacing a HDD is really easy and pretty cheap. then you just have to restore the computer, either from a backup, or from the restore discs that probably came with the computer.
sometimes those computers dont come with discs and you are supposed to make them yourself. if you havent made them, do it now. if the box dies and you dont have the restore discs, you will need to call HP and pay for them.