Posted 23 November 2008 - 05:26 AM
It could be the hard disk that's failing but you can download and run a diagnostic tool from the disk manufacturer's website to confirm this.
If you know the brand of the hard disk (eg Seagate/Maxtor (Maxtor belongs to Seagate now), Western Digital, Samsung etc.) go to their website to get the diagnostic tool creator for either floppy or cd-rom. Boot your PC from the floppy or cd you just created. It will start in it's own operating system (usually a version of DOS) and present you with a menu for various options including the diagnostic test.