|yeah it sounds like your hard disk drive (HDD) is on its way out, if it hasn't left the building already. on your NEXT SUCCESSFUL boot, pull all your data off because it may be your LAST.|
do you have another PC? is your current HDD IDE or SATA? You could always try plugging it into a different port on the mobo, using a different cable. Failing that, I would try attaching it to a working PC as a slave drive and trying to retrieve the data that way.