When I put the following a bat file and run it as scheduled task, I see that the webadmin.exe process starts but it never seems to create backup:
wbadmin start systemstatebackup -backuptarget:\\server\foo -quiet
This seems to run fine when I run the bat file directly. I have the scheduled task configured to run with the "highest privileges". The share doesn't use windows authentication but it is a mapped network drive.