Just put that error code into Vistas own "help and support" and it comes back as a windows update error.
Has the backup routine worked OK before ?
Just going off your question I'm not a great fan of Vistas backup using DVD's. Too slow and messy and prone to errors. If you only have a few gb of personal stuff to back up a flssh drive or two, or SD cards are IMO much better.
And best safeguard of all, a program like Acronis that backs up the entire system.