A friend of my has an HP Pavilion ze4400 laptop with Windows XP on it. A couple of months ago his hard drive was replaced and has worked fine until yesterday. He boots up his computer to find all his personal files gone, all his programs not working, and all the default software back on it. I took a quick look and it appears like the computer reverted back to the original state. I used a hard drive recovery tool and found over 15,000 files "lost" on the drive. I'm not aware of any virus that could cause this and I don't think this laptop has an image backup (like some Dells do). One interesting thing is that there are Administrative logs before Windows reset. The only anamoly I see in them is that there over 20 errors for the hard drive. The error is as follows: The device, \Device\Harddisk0\D, has a bad block. The only other useful information in the log is the Event ID which is 7. If anyone has any ideas on this I'm all ears.