Whenever I change the network configuration to NAT for a virtual machine running under Virtual PC 2007, I get "A duplicate name exists on the network." error.
There is no other machine on my network with this name and running the VM in any other network configuration doesn't cause this error.
This seems to be a common problem with Virtual PC 2007 based on a google search but no-one seems to have a solution to it.
So far, I've discovered that turning off NETBIOS over TCP causes the problem to go away but I need to join this VM to a domain and you can't do that if NETBIOS over TCP is turned off.