Whats happing is your game is closing in a non traditional way(ie; screen goes black then back to game thats a crash) when you change maps.So when the game goes to load the next map the server see's your already on the server and trying to get on it again which you can't do so then it gives you the qport error. A qport is 28960. This was suppose to be fixed in patch 1.5 I think. How to fix it well thats a big question. You have to find out why your game is crashing when you change maps. I would start by turning stuff off one at a time. So play the game with no x-fire and see if it solves your problem. Then turn off your antivirus and try and so on. Update punk buster, See if it happens on just one server or on all 4 servers. All I can think of good luck.