Pulseaudio glitches when playing music

[Spider]

Binary package hint: pulseaudio

When playing music with Rhythmbox is glitches and scratches, running pulseaudio from the console gives me the following (repeated, MANY times)

E: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is a Linux bug. Please report this issue to the ALSA developers. We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail_update() returned 0.
I: module-alsa-sink.c: Underrun!
N: module-alsa-sink.c: Increasing minimal latency to 16.00 ms
E: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is a Linux bug. Please report this issue to the ALSA developers. We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail_update() returned 0.
E: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is a Linux bug. Please report this issue to the ALSA developers. We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail_update() returned 0.
I: module-alsa-sink.c: Underrun!
N: module-alsa-sink.c: Increasing wakeup watermark to 8.00 ms
E: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is a Linux bug. Please report this issue to the ALSA developers. We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail_update() returned 0.
E: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is a Linux bug. Please report this issue to the ALSA developers. We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail_update() returned 0.
I: module-alsa-sink.c: Underrun!
N: module-alsa-sink.c: Increasing minimal latency to 26.00 ms
E: module-alsa-sink.c: ALSA woke us up to write new data to the device, but there was actually nothing to write! Most likely this is a Linux bug. Please report this issue to the ALSA developers. We were woken up with POLLOUT set -- however a subsequent snd_pcm_avail_update() returned 0.

alsa-info.sh results are here:
http://www.alsa-project.org/db/?f=13a6834f1de4bf161dcf645f1e85d33550e0c975

Description: Ubuntu jaunty (development branch)
Release: 9.04 Updated Tue March 03 at 9:40 am.