I ran into an issue where I could not enable the VMRC in MS Virtual Server 2005. I would check the box and save the settings but it would revert right back to being disabled. Turns out that VNC server happens to run on the same port, 5900, as the VMRC. So if you are running VNC you have to change the port for either VNC or VMRC. I wish the control panel would have just thrown an error but it's those sort of things that keep life interesting... ;-)