Loss of Audio in Ubuntu

Some users of Ubuntu 9.10 have reported that, after flying in X-Plane for anywhere from a few minutes to a few hours, the sim will suddenly stop putting out sound, although it will still take input from the joystick, the menus will still work, etc. After this happens, the sim will lock up when the user tries to close it.

This is caused by a conflict between X-Plane and PulseAudio which, curiously, seems to be limited to Ubuntu 9.10. This can be fixed either by removing PulseAudio entirely (as described here in the Ubuntu forums) or by upgrading to Ubuntu 10.04.

Both the problem and the solution are described further here on the X-Plane.org forums.