Maybe I’m the only one, but I put one of my new Hyper-V imgages into a difficult state the other day by choosing the wrong network type. What I mean by this is that when Server 2008 came up (for the first time) and saw it was on the network (it was bound to the virtual NIC attached to the physical NIC on my laptop) it asked me if I was on a public network, home network or work network. I wasn’t thinking and said it was a public network. That makes it harder to access your VM as a UNC. I don’t know all the differences to these different settings, but I do know that if you choose public, that it isn’t discoverable from the netbios name.
Make sure you use either Home or Work network.