Snapshot Error

SSR 2013 R2 11.1.2.51177 -- Win 7 Ultra 64.

Backup has worked OK for the past few months.  Today I am getting the following errors.  I am attempting to backup to my desktop computer with only two hard drives "C" and "U".  I did a search, but could not find a solution.

 

Error EC8F17B7: Cannot create recovery points for job: C to U.
    Error EC8F03EA: Cannot create a virtual volume image of the selected drive.
        Error E0BB00B5: Snapshot error Error EBAB03F1: Following Operating System error occurred while performing requested operation: 'Unspecified error.'. (UMI:V-281-3215-6071)

Details:
Source: Symantec System Recovery