Replying to Playing Warcraft Iii Lan Using Wireless Thomson Tg585 V8

I've just got a new cheap DSL router - Thomson TG585 v8 which i setup with firewalls disabled and wirelessly connected two computers to it.

Now i was testing Multiplayer between these two machines running Windows XP for playing Warcraft III

Funny thing is... Computer A can create multiplayer game and Computer B can view it and join the game, where as when computer B tries to setup a game, Computer A can't view/join this game

I've tried disabling both Window XP Firewalls on both machines with no luck... so i'm left with the assumption that its got to do with some setting on the Router

Setup Details:

Wireless Router Thomson TG585 v8
PC A - Windows XP
PC B - Windows XP

Both PC can connect through router to Internet without a problem