Game crashes after picking a champion

Couple of days ago i had everything normal. I had windows 8 system, but then it updated itself to windows 8.1 and then problems started. I can launch Lol client but i cant play the game. After champion select, when it should come loading screen, it shows error and send me back to reconnection page. I have looked and tried different solutions like changing logitech files names and reinstalled lol, but it still doesn't work. I have send many bug reports to riot and hope to get it fixed soon. So, can anyone help me ? It tells that the problem is about firewall, but it is not. I have disabled firewall and also allowed LOL through firewall, but it still doesnt work.