I am having the same problem… Though it seems to be more with Files Backup, than with Category Backup.
The files that are getting the 8968 seem to be some from Thunderbird (Mozilla e-mail); the e-mail folders, and some Registry Export files. Thunderbird was NOT running, and the Export files were from a few Months ago, so, should NOT be Using any programs.
There is one more problem, that I noticed, with File Backups. It isn’t there, Now, but I have a screen print showing two lines from the “These files failed to back up.” The two lines have Nothing in the Name column. In Size, it is 0.00 KB. In Date, it is 12/31/1600 7:00:00 PM. In Reason, it is “The operation completed successfully.” Location shows as a blank.
Why would something in Failed to backup, have “completed successfully”? Where did that Date come from?? What computer created files in the 1600’s??? (;->