Seems like steam was messing with me and was launching the game in DX9 instead of DX10, so that was the main problem. Works now just fine, but it took a while to figure out..Keep your save before reinstalling everything. Or normally your mate should have it.
So thanks for the help.
I am planning on trying the new versions in the future, how much have they been tested in MP?
(Talking about the ones in Stablest Multiplayer subfolder on Google Drive)