Backup error 0x81000010

[Guest hst12]

I'm getting the following error from Windows backup:

 

The backup application could not start due to an internal error:

 

You must be logged on as an administrator to perform this task. (0x81000010).

 

My profile is a member of the Administrators group.

 

The backup used to work but now fails with the error above if I try to use the manage space or change settings options.

 

Does anyone have any ideas?

 

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