TBH im having the same issue on my windows 7. I have the same problem of being able to play a skirmish no problem, but when i swap over to multiplayer and join a server it boots me out to main menu saying there's NO ERROR TEXT. I've followed through with the OP with the fixes, attempting a third time of reinstalling the game and im going to try and make sure my steam name and game name are the same as soon as it finishes downloading. If the OP wouldnt mind telling me what the fix was, i would greatly appreciate it! been looking over 4-5 pages of forums so far lol