Possibly faulty hardware, but to start with I would test the hard drive if only to eliminate that as the culprit. You can't test it with any Windows-based diagnostic utility so you'll need to test it with a diagnostic utility that loads from a bootable CD.
Try SeaTools for DOS
or Hitach Drive Fitness Test (CD Image)
Both downloads are ISO files from which you can make a CD using IMGBurn
on a working PC: http://www.filehippo.com/download_imgburn/
When you've made the CD, boot your DV6 from it and the testing software will shortly load.
(You may have to bring up the Boot Menu on your PC & select CD/DVD Drive as the boot device, or go into BIOS Setup and change the first boot device to CD/DVD Drive).