Excuse my bad english..
I can't join any server, neither single nor multiplayer. It named the error, that my save files are curropted, but I fixed it with the manuel and try to uninstall and install the game after try to join. But it's also the same problem after do this.
The only thing that could be caused this, that I joined the hosted server by my friend and my PC crashed after joining.
Hope you understand what I mean :)