Backup MyPC v6 (Build 600B650 - REU)

Two folders are reported 'not found' after a differential backup.
Both folders were on the desktop, namely:
1. Actual T189 ECA submission
2. Dummy T189 ECA submission

I had previously deleted these two folders from the desktop.
(They each contained a single zip file)

How can I prevent these errors being reported on backup?
(Neither of the folders are visible when I open the differential backup job.)

David