I purchased Arma CO last night on Steam. I have downloaded and installed both, I can start and play all games except when I launch Operation Arrowhead and select CO at the bottom. After I click it, there is like a small DOS screen that pops up for a sec then goes away. Then nothing happens, the little check boxes dont come up like on the other games. Ive tried downloading the new update, reading on every forum. I cant seem to find someone else with the same problem in a thread. If you would please guide me to what is wrong it is greatly appreciated. I want to get down on some DayZ mod, and also enjoy what Arma offers that other shooters lack.