OK no ones looked into this but perhaps it is server based (at relic) only why else would you have to log in and only have the options of the servers that show up ingame. Where are the IP’s if someone is truely hosting it?. Why couldnt you just have the option to type in an IP address if that was the case I think the only function of the host in this case is to admin the conditions of the game. Once the game has started they have equal rights so in reality it is how your ping (your pc and it OS and other peripherals) can deal with synchronizing to everyone else.
perhaps MAX should create a new partition on his PC and reinstal a version of XP and see if it makes any difference