I have installed both arma 2 (free) and arma 2 Op. Arrowhead, and ran both separately via steam. While both of those run fine individually, when I try to play Arma 2 CO, I can't get in. The command prompt pops up (and stays up), but then nothing happens. Both installs are clean (I reinstalled both of them, and haven't tampered with the files at all, so there is no dayz on it, or any other mod). Does anyone know what I can do to fix this? I tried looking on the internet to solve the issue, but I haven't been able to come across anything exactly like my problem. Any suggestions are welcome - thanks!