I didn't make it!
Well my friend had a problem with the latest bf2 patch all the things on the internet we tried and well they didnt fix it
but finally i found a problem he had the typical lag issues etc so i thought it was the firewall the firewall he is using is macafee so anyone with a different firewall im afraid this might not help you.
but what had happened is he installed the patch witch modified bf2 usualy a alert pops up saying this application has been modified and you allow the ap access to the internet. this did not happen did for me but not for my mate.
so while bf2 was running i disabled the firewall then re-enabled it and it noticed the modification straight away and he hasnt had the laggy server list or gameplay like he did when he installed the patch.
im no expert but i think it is something to do with the patch it must confuse firewalls or something
hope this helps:)