Thanks Bob_Clark,
"New must be added with:
omniinetpasswd -add { User@Domain
Domain\User }... [Password]"
This sorted the same issue for me.
We changed the password that the IDB services run a while ago, but since the service account logins were updated at the time all looked good. I didn't realise that HPDP kept a copy of the credentials within the IDB for the backup process to use!
Cheers
Chris