Hosting problem

[aslan2323232]

heya
a mate and me have been trying to fix my portforwarding problem for a month now
in the end we gave up and fixed his instead
he hosted a game last night and i was able to join no problem
however when he launches the game he cant ping my computer (the headstone symbol appears beside my username)
ive never had a problem joining a game before and neither has he
whos computer is it and how can we fix it (:

PS ive looked in the help section there was nothing remotly related to this problem as far as i can see

[simple_faith]

His firewall/anti-virus maybe blocking EE.