replace the drive. one quick test to do is to boot off of a bootable disk such as norton or your restore disks. im going to guess you have a toshiba laptop so here instructions on how to test the drive, if not a toshiba repost and ill give you similar but different instruction. when you restart the machine watch the first screen it should say somethign along the lines of press esc or f12 for to select boot device. with a bootable disk in choose this then choose the cdrom. if it boots to the disk then you have a windows issue, if you goto windows, then the drive is bad. booting off the disk superceds windows, so if its a windows issue it will work, if not then its bad,