I had an issue with System Center Virtual Machine Manager 2008 R2 today. I had been working for months and today I was not able to start it. The error I got was:

VMM is unable to perform this operation without a connection to a Virtual Machine Manager server. (Error ID: 1615)

 I started the console on the same server as VMM was installed on. After some searching I found this article.
What worked for me was:

Start a Command Prompt with Run as Administrator:

osql -E -S SRVVMM\MICROSOFT$VMM$ -Q “USE VirtualManagerDB; EXEC sp_changedbowner ‘sa’”

 Where SRVVMM is my VMM Manager Server Netbios name, and the instance is the default “Microsoft$VMM$.