Linux guest audio stops working when default audio output is changed on a Windows host

[hakuya]

I'm running VirtualBox 3.1.6 on a Window 7 64-bit host. My guest is a 32-bit Ubuntu 9.10 (Karmic) install. I was also previously experiencing this issue on VirtualBox 3.1.4 on Window Vista 32-bit before performing significant hardware upgrades to my computer. The guest did not change: I simply copied the VDI over.

My computer is connected to both a small monitor and set of speakers for when I use it for work, and the computer is also connected to my HDTV and digital sound system for when I use it as a home theater PC. So I frequently change the default audio output depending on the current use of the system.

I like leaving my VM running in the background doing some processing tasks or other things, but I've noticed that every time I change the default audio output device in windows, audio becomes hosed in the VM. No audio plays back, and if I try to play a video in mplayer, or a youtube video via flash on firefox, playback hangs after about two seconds (unless on mplayer I add '-ao null' to disable audio output). The only way I can recover from this state is by restarting the VM. Restarting ALSA or pulseaudio does not seem to solve the problem.

I also have a Windows XP VM, but the Windows XP VM does not seem to be affected by this issue. When I change the default audio output on the host, XP's audio is properly redirected to the new default audio device.

[aeichner]

Please reopen if still relevant with a recent VirtualBox release.