extremelyloudsound

My game continues to crash without hanging up, anywhere from 10 to 30 seconds after I join a server. The error "arma 2 reinforcements has stopped working" displays . I don't believe it is a hardware problem because I can play Arma 2 flawlessly in singleplayer mode with no crashes or hangups. This only happens after I join a multiplayer game, and it runs smoothly for less than a minute. I am running Arma Combined Operations when I launch, everything is installed correctly, updated, and triple checked. I cannot figure out what I am doing wrong here. Thanks