I setup backup of my Windows 8 laptop with Windows 7 File Recovery (known as Backup and Restore in Windows 7).

Backup of files runs successfully. But if I try to create system image, it fails with error 0x807800C5:

Error details on the dialog:

The mounted backup volume is inaccessible.

Error details in the system log:

There was a failure in preparing the backup image of one of the volumes in the backup set.

I save the backup to a network location, WD MyBookLive.

 
Edit:

I tried some of the steps suggested in the various thread about this issue:

1. Cleaned up the backup location:

   1. Removed MediaID.bin in the backup location.
   2. Removed folder <ComputerName> from WindowsImageBackup.

   3. Restarted backup resulted in the same error. However, the error dialog shows slightly different error message:

      The specified backup disk cannot be found.

      

2. Performed System File Check by running sfc /scannow. It showed no errors.
   Running backup failed nevertheless.

I tried searching Google for error code but I've found no solution so far.

Update:
I submitted technical support request to Microsoft. The first suggestion was to clean boot, but it didn't help. I pointed out that I had tried all the methods from the same problem on MS Answers, and nothing had helped.