What causes a CHKDSK to turn off the computer?

Windows 7 Home Premium SP1

Trying to back up C:, D: & System drives using Windows Backup, Acronis, and Macrium all fail after about 65%. Acronis screenshot attached. The other programs don't even give that much info, or I couldn't find logs. How do I turn on deep logging for any of these programs? How can I find out what file occupies the sector identified in the Acronis error?

I ran CHKDSK C: /R /F on bootup and left for work. I come home and the computer's off. I ran it in the evening and it got into Stage 4 of 5 for a long time. It seemed to be stalled at 79% for a long time but then it finally went on to 80% so I figured it was just on some big file. I did something else for about 15 minutes and then looked back and my computer was off again! Backups continue to fail. What causes a CHKDSK to turn off the computer? I'm baffled! I hope I can solve this without staring at CHKDSK for 45 minutes only to find out the info I need just flashes by.

Thank you,
Bent Franklin

I still don't know what caused the backups to fail, but I figured out what was happening with CHKDSK. Last night I ran it in a DOS window from the System repair disk. It got hung up on different steps but always seemed to keep going eventually. It was stuck at one point for a while and then the screen started flipping out and then it froze. It wouldn't reboot. So I thought I was hosed. But I took it apart and noticed it was really hot. I think it overheated, which would explain all the shutdowns. After a few hours I started it back up and I'm back in business. Now I have to figure out how to get a backup with a disk that has a major problem.

Of course that doesn't answer the question: Why would CHKDSK cause it to overheat just because it got stuck on one sector of the disk? Why didn't it just mark it as bad and move on?