If you have a Hyper-V server in a workgroup and you want to manage it remotely from a client computer in a different domain, then you will have to configure the server to allow connections from a client in a different domain. the process is a pain, but luckily there is a script that do that for you with just one click. download the script from this link http://code.msdn.microsoft.com/HVRemote and look at the 10-second guide in the front page. the setup I did was Client domain, Server workgroup
follow the instructions in the link above, and let me know if it works for you. I still cannot manage the server through server manager snap-in, but I think that’s an issue with my client computer.