My old problem is back after the new update

I would appreciate your help guys. Before the new update (patch) I had the same problem, but I solved it by choosing option 2 for launching the game (i forgot how it was called, but there was a recommended one and that other one i used). That way I managed to trade and talk to other players and also play coop via hamachi.
Now after the new update, that other option doesn't exist anymore and I have my old problems back : the game crashes often, I can not talk to anyone on the trade (always when i click on someone I got "the player doesn't exist message")..
So before the patch the game was playable for me, now i'm frustrated... I tried many things, I guess it has something to do with me changing ports/port forwarding and also I think I changed my ip settings in order to try to play coop without hamachi since not too many people are using it.
If anyone has any ideas what could I do, I would totally appreciate any kind of help