Hi,
I just discovered an option to analyze the disc for errors (right click drive/ advanced) . It would be sensible to have this option as default followed by the analyze and then defrag. You could always put an option for this to be toggled on or off. I have had to do a manual chkdsk until i discovered this. Also, defraggler should stop and warn the user if there is an error on the drive and steps to take to correct the problem.
Thanks for a great free tool BTW