Sound stops working after playing a game

[Sam Morris]

I'm using VirtualBox 2.2.4 on Vista Home Basic with Debian 5.0 as a guest.

If I switch away from the virtual machine to play a game such as Half Life 2, then when I come back to the VM, sound doesn't work. As far as the guest is concerned, the sound is going _somewhere_, and there are no errors; the virtual machine is simply silent.

If I close the virtual machine, and save the state, then immediately start the virtual machine again, sound comes back and everything is normal (until the next time...)

[Sam Morris]

vm log