After clicking the login button it appear an error says 'An error has occured.Please check your network connectivity'.I bought this game from steam since it make discount for the game in the summer sale about 2 weeks ago (I forgot when) but after installing there is no problem at all (single player/multiplayer) and 2 days ago I could still playing the multiplayer without the error but on the next day the error keep occured until today.I had tried many times loggin in,still can't.

I hope you all can help me to solve this annoying problem...(Please dont just tell me you had the same problem but not tell me how to solve it like in other forum (in the internet).)

Finally,Really sorry for the bad english...Hope you all understand..!

If you're having issues with logging in, check if your ports are forwarded.
If they are, but you still cant login:
-Remove crysis 2 from firewall exceptions
-Restart computer
-Manually add Crysis2.exe as a firewall exception
-Restart
-Try to log on, it should work