Searching that error on Google came up with quite a few suggestions.. Just a couple of links below:

http://au.answers.yahoo.com/question/index?qid=20080112081600AA3YXER

http://blogs.technet.com/james/archive/2008/02/06/vista-backup-errors-and-apologies.aspx

Personally, I don't use the XP or Vista backups to perform a backup.. Since the computer Recovery Discs or your OS disc will bring the computer back to a factory state, I choose to simply backup important files from "My Document/Documents" such as pictures and music.. Either that, or I use a mirror/ghost program such as Acronis, etc. It's your choice though..

Hope this helps.

Grif