I was doing a defrag and it kept stopping because of a conflict with the Volume Shadow Copy service. A quick Internet search turned up a site that recommended disabling the Volume Shadow Copy while defrag is running. http://forum.soft32.com/win4/Defragmenting-pauses-volume-shadow-copy-ftopict212207.htm I did and that fixed the problem. The site said to leave it disabled if I don't need it. It didn't say how I could tell if I need it. I left it disabled and everything seems to be working OK. How can I tell if I can leave it disabled or if I need to reenable it?