[Drdul]

Dave showed me how to access the log for Super Duper!, and it turns out that it was stalling out on the huge file that Parallels creates, because I had Parallels running at the time that SD was scheduled to do a backup. It works fine when Parallels isn't running, so I've simply rescheduled SD for a time when I'm not likely to have Parallels active.

FWIW, Entourage can cause the same problem, so that (and a bunch of other reasons) have convinced me to stick with Apple Mail.

Cheers!