Connecting two computers

[Gazoo]

I will attempt to answer all questions here

1. Both comps are running Win XP
2. Router is a Network Model NR041
3. DHCP is enabled in router
4. No port forwarding or filtering have been assigned
5. I am using FLAM on one of the comps
6. If one is connected and try to connect with the other I get a cannot connect message and then the other comp will freeze and have to be rebooted
7. They are two different account ID's
8. As stated these are two seperate accounts and we just want to play together on same server and like this Mod(father, son competitive thing you know( he of course thinks he can kick my butt))
9. I suppose we could just do this internally but would be fun to go against others too

Thanks for all input
Gazoo