I have a server 2008 server happily running as a hyper-v host. The server has 2 NICs, with only one connected at the moment.What I want to do is enable the second nic and plug it in to a standalone development network (a switch which isnt connected to the main network). I've made the physical connections, but the second I plug the second nic in to the switch, I loose all connections to the main nic, and cannot connect or even ping the server. As soon as I unplug the second card itre-appears.Firewall is turned off.Does anyone know what could be causing this?

Problem solved. Firewall was turning itself on as soon as the 2nd nic was connected.