Mainstage Stops my audio output on several devices

Mainstage seems to work perfectly until I switch to a patch my computer doesn't like. With the built in output, and two different interface, two different keyboards, or no keyboard, as soon as I change patches there is no audio. Just one pop and its all done. Midi notes are still being played and the meters are moving when I play, but there is no audio. If I open itunes and play a song, nothing comes out of the output either, so the problem is not contained to mainstage. If I switch outputs and switch back, the sound comes out again, but as soon as I switch patches it happens all over again. Any advice?