After I try to launch a game and it shows in full-screen mode i only get error "sign in couldn't be completed". As far as I was able to find out it's not caused by any of these:
- my internet (i tried on two different connections)
- my firewall (doesn't matter if it's disabled or not, logs are the same)
- antivirus (again, switching it off doesn't affect log)
Also, i have latest nvidia drivers and I reinstalled the game. Didn't help. Reboot either.
Yesterday game was running kinda-fine, only it hanged sometime on game score-screen for some reason.

Anyway, here's launch log as nothing else was generated: http://pastebin.com/gq5hRrTw