got this while googling
Also, this may helpFixed here.
Goto computer properties | Advanced system settings | System protection tab.
Uncheck all drives, hit apply. This will turn of shadow copies and clear them.
Reenable the drives, hit apply. Since you just cleared them all you may also want to hit the create button to repopulate at least one.
Run the backup again.
---------- Post added at 12:44 PM ---------- Previous post was at 12:37 PM ----------
Another useful link