The error message I posted came from the pgAdmin log. The pgAdmin error message window states "An error has occurred: Execution of command ' -i -h localhost -p 5432 -U postgres -F -c -b -v -f"E:\Backup\test1.backup" npcat_db' failed (error 2: the system cannot find the file specified.)"
Thanks Michael - I've committed a fix to make it actually find pg_dump/pg_restore correctly in the first place, and another to prevent the backup/restore options be made available if pg_dump/pg_restore really are missing.
Regards, Dave.