I have Hyper-V added 

I recently attempted to add a new virtual machine to my Hyper V server but realised there was not enough memory on that server to cope with another machine. I reduced the memory allocated to three other machines and tried again.

After adding the machine, with no operating system yet, I suddenly cannot access any other machines from the Hyper V console.

I double click the machines in the list, or select them and click "Connect" - there is a slight flicker and nothing else happens?

I have since removed the partially created machine. Restarted the server (a couple of times actually). I've checked the event logs...nothing.

I can start any of the virtual machines and connect to them remotely once they are running but I cannot connect to them, on the host, via the Hyper V console.

What could the problem be? Where should I be looking?