Multiplayer game Network error

I am trying to play multiplayer games (C&C, Rise of
Nations, etc) on my two home computers. They are
networked using a cross over cable, and the network is
working fine. But when I go to log onto the network
under multiplayer game my laptop tells me it is unable to
connect to the network - but my PC connects to the
network fine. I cannot tell where the network connections
are set up differently on the two computers. The games
load ok on both computers. Any ideas as to what would
make this error occur?