I use Acronis True Image 9.1 on my system. I was having a lot of difficulty with the unmounting of images within the application...the drives would unmount, but the files would remain locked, and not remove themselves from the Acronis interface. After a lot of reboots, I narrowed the problem down to only occurring when sptd.sys is enabled. As soon as I disable it, the image files will unmount and unlock correctly. I did not have this problem at all on systems w/out DTools.