My bf has the same problem. Worse than that, he deleted the cfg file that was an advised solution, and then the screen turned black......now its blue and it says to register or sign up but the buttons dont work. This is all through steam, also happening today whilst last night game worked fine.

He tried uninstalling and reinstalling and nothing works.
I also have the game through steam and its all fine. He updated everything there was and it still doesnt work.