I have had the exact same problem. 250 Gb SATA drive, XP SP3, Defraggler 1.10.143. After >20 hours, only defragged 15% of the drive! Previously (say, last week), it worked perfectly. Not sure what has changed.
I'd be happy to follow the previous post and run in debug mode, but isn't the debug log generated only if Defraggler finishes? If so, then not likely, since I'm not going to wait the days and days it might take to finish.