My situation: I have installed SQL Express on my machine, while logged in as a domain user. I work remotely so I need to connect to a VPN to be on the domain, but I often prefer not to work while attached to the domain so my packets don't have to travel across the country. My user account has local admin rights (win 7).
My problem is very similar to this one. I receive the same error message when I try to do "admin-y" things, like creating new databases or adding database diagram support to existing databases. The catch is that the error only happens when I am NOT attached to the VPN (and therefore my machine cannot reach the domain controller).
Is there a way to allow SQL Server to trust my login credentials when I'm not connected to the VPN?