problem: Windows 7 backup won't run or has stopped running
impact: Your stuff is not being backed up!
solution: Try creating a backup user or simply logging outI had a user who's backup stopped working. After consulting with Dr. Google, non of the usual solutions would resolve the issue.
One person reported solving the issue by ensuring no users were logged in when the backup schedule ran, which makes sense, seeing as the error is related to some kind of file sharing violation.
This got me thinking, perhaps the usual user account had some processing running that were locking out some files. So I had the idea to create a backup user account, to see if the back up would run under that account. It did.
At the time of writing, I don't have any better suggestions, other than trying one of the above. It would seem that for my user, the error was related to a process running under their normal user account, locking out some files. Until that process is found and killed, it would seem that backing up while logged in as that account is not going to work.
P.S. Its worth noting, I was attempting to do a full backup for the computer in question.