Mark --

Try simplifying things. Open Script Editor, and then JUST put in:

do shell script "diskutil mount disk0s5"

Run that. Does it work?

Yes it does :)

Well, then, it should certainly work "live". You might want to do a "display dialog" in there, or something to show that it's running. If not, are you certain that you're recompiling it by changing your schedule?

I just did this, and again it didn't mount the disk (then superduper quits after approx 5 secs):-

-- SuperDuper! scheduled copy script template (c) 2005-2006 by Bruce Lacey. Published by Shirt Pocket.
-- Script by Dave Nanian and Bruce Lacey

on beforeRunningCopy()
do shell script "diskutil mount disk0s5"
end beforeRunningCopy

on afterRunningCopy()
do shell script "diskutil unmount disk0s5"
end afterRunningCopy

Yes I am recompiling by editing the schedule (I know this because occasionally when I've got the syntax wrong etc. then after "editing" the schedule it says there's a script error).

Try telling Finder or System Events to do the shell script. So:

tell application "System Events" to do shell script ...

Yes!! It's worked!!

Good work Dave :)

Yay! Finally... (whew)