This is one of the more common errors we run into. There is an object in the database that no longer exists. Follow this article to clear up 801 errors, and bookmark the article.  ;)  This is a SQL script that should be run with the VMM service in a stopped state.

Performing an operation in Virtual Machine Manager fails with error 801
http://support.microsoft.com/kb/2756886

 

 

  jonjor