Vista - Backup & Restore center

I am using vista Home premium as my OS. Back in January I did a full file
back up using the Windows back Up and restore center, which was successful. I
now get frequent reminders that i have not done a back up in the last 30
days.When I click on this icon to authorise a back up, the backup status and
configuration window opens and I see that the automatic back up facility is
turned off. The 'Backup now' 'change setting' and 'turn on automatic backup'
are all greyed out.
When I attempt to set the automatic function, I go through all of the
options, ie selecting where to back up to etc. I click on 'save and commence
back up' and then get a message 'Task Image is corrupted or has been tampered
with. error 0x80041321'
Any ideas to restore this function would be appreciated and my latest files
are not being regularly updated and to have to do it manually is a bit of a
drag. excuse the pun!!