Can't run Alter Table command due to locks I'm unable to drop, delete or alter a database in my Local SQL Server instance.

I have run sp_Who2 and there don't appear to be any processes using the database apart from a process which gets spawned by my issuing the Alter Database command (I do this against the Master db). This process has a Wait type of LCK_M_X and a value of -2 for the Blocked By attribute.

I have issued KILL commands against them and I've restarted all the related system services and my machine a few times but to no avail. Is there anything else I can try?
Stop (do your alter) and start DTC and all will be fine.