Running Ubuntu 14.04 LTS x64. When I am playing Team Fortress 2 through Steam, everything is fine until I start using my microphone. After about 20-30 minutes or so, all audio stops working. As far as I can tell in this state, the microphone still works, but I can't confirm due to lack of audio.
Update: I also have setup Counter-Strike: Global Offensive through PlayOnLinux/Wine, and the sound also stops working in this game, generally when I move from one server to another.