There is another reason that I see that corrupts hard disks and that is a bad RAM location. Sadly you find many that can't accept the passing of a machine but you let them fail until they give up and either fix the machine or replace it.
Good luck in finding the cause but in most cases you do hear the owner rattle on about windows locking up, etc. which is a fine clue.
I have windows XP, and a dell insiprion 6000. The last three times I have ran a defraged my hard drive it has become bad. After running my computer would act normal untill i shut it off, then windows xp would not load again. I get a blank screen with a blinking dash in the top left of the screen. They have been under replaced for free by seagate so i am wondering. Have i had bad luck with hard drives or could there be a problem with other parts of my computer?
Thanks for any advice