The error E000FF00 could point to a few possible causes. To narrow this down, could you provide the actual error message from the JobLog. Also, a) What version/spack of BE was used for the Backup. b) What Exchange version was backed up.
I have not run into this myself however have you taken a look at reregistering the VSS as described in TECH70486. Also, it is sometimes good to consider upgrading to the latest Service Pack or Patch for BE 2010
