Hi Daniel,
When that error occurs, go on to the
\\batman server, open a command window, and run:
vssadmin list writers
You may have to scroll to see all of the writers listed. Check for any writers that either show a status that is not "Stable", or that show any error in the "Last error:" field.
Frequently, simply rebooting the affected server may resolve the issue. If not, Microsoft has a number of patches available, depending on which VSS writer is causing the failure.
Regards,
Greg