joraneyGo to controlpanel, then find sound, then go to communications and hit "Do nothing", if you're running on windows 7. I'm not sure about other operating systems, but this fixes the mumble cutting out for windows 7 atleast.
Also, you know how to run in windowed mode and make it look like fullscreen, right?
dude. i love you so fucking much!
It worked!
I'm so gratefull because this has been a longterm problem.
Was stupid i didnt think of it, but i'm so glad you knew :D.