Thank you very much for including this additional feature, that I think makes backup more intuitive.
As always, a couple of problems
When activating the script from within MM <Tools\Scripts\Backup>
and selecting "Backup" with the configuration set as screenshot #1 shows, the backup runs normally and completes without issue.
On shutdown however, the error message (screenshot #2) pops up, followed by the "backup completed" message (screenshot #3)
Without Backup 3.3 loaded I do not get this error when shutting down.
Win XP Home SP2 + all current updates
Hope this helps you to track this error down.
#2 Error Message
#3 After Backup has Completed