As I recently upgraded to karmic I started to see the following stuff in the logs when I run VirtualBox:
Oct 30 18:14:34 apocalypse pulseaudio[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)io[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)
Oct 30 18:14:34 apocalypse pulseaudio[2813]: alsa-source.c: Resume failed, couldn't restore original fragment settings. (Old: 65536/65536, New 1073676288/65532)
After a while the logs grow to large sizes and fill up all of my /var partition. In VirtualBox there is an option to choose between pulseaudio and alsa for sound, but it seems to have no effect. I am using virtualbox-3.0 packages, not the ose version. My system is up to date.