web GUI can't launch from machine on the same network

[cko015]

I'm seeing a very weird problem where I launch a mozilla browser from the machine and type in the IP of a machine on the same network that contains an applet to launch a GUI web browser. The strange thing is that the web browser will launch from a machine on a mozilla session from a machine on a different network. There are no other variables other than the network, and I don't think our switches and routers have anything different between the two networks.

The other intersting thing - is there's a similar machine that launches a web browser on the second network and the same thing happens, I can't launch the GUI from the same network but can on the machine from the different network.

Any ideas?