My computer tech was on vacation and I brought my unit to Comp USA. It seems a registry file had corrupted. They kept it for almost 2 weeks (giving me a song and dance each time I called)and then said they would have to reformat the hard drive and I would lose everything.
After paying the $40 fee for a new SCSI card which I didn't need, I took the computer to my usual tech who repaired it the same day and I did not lose a thing. That was about 4 months ago and I will never trust CompUSA again.