When running PulseAudio, if I'm playing music via any source (Exaile, Totem, Flash in Firefox or Chromium, VLC, etc.) every few minutes the audio will skip once or twice.  top doesn't show any process eating CPU any more when it happens.  dmesg doesn't show anything.  Nothing else seems to be affected.  It doesn't seem to happen regularly.

I just installed Ubuntu 12.04 from scratch (with pulseaudio 1:1.1-0ubuntu15), but the same thing happened in 10.04 on the same hardware.  Uninstalling the PulseAudio packages and going back to ALSA gives me no issues whatsoever, which is how I know the issue is with PulseAudio.  I'm using my onboard audio device:

$ lspci | grep Audio
00:14.2 Audio device: Advanced Micro Devices [AMD] nee ATI SBx00 Azalia (Intel HDA)

Following mailing list instructions, pulseaudio -vvvv --log-time shows during a skip:

( 684.030|   5.000) I: [alsa-sink] alsa-sink.c: Underrun!
( 684.030|   0.000) I: [alsa-sink] alsa-sink.c: Increasing minimal latency to 26.00 ms
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: Latency set to 26.00ms
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=60952
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15944
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: Latency set to 26.00ms
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=60952
( 684.030|   0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15944
( 684.031|   0.000) D: [alsa-sink] protocol-native.c: Underrun on 'ALSA Playback', 0 bytes in queue.
( 684.036|   0.004) D: [alsa-sink] protocol-native.c: Requesting rewind due to end of underrun.
( 684.036|   0.000) D: [alsa-sink] alsa-sink.c: Requested to rewind 10940 bytes.
( 684.036|   0.000) D: [alsa-sink] alsa-sink.c: Limited to 3320 bytes.
( 684.036|   0.000) D: [alsa-sink] alsa-sink.c: before: 830
( 684.036|   0.000) D: [alsa-sink] alsa-sink.c: after: 830
( 684.036|   0.000) D: [alsa-sink] alsa-sink.c: Rewound 3320 bytes.
( 684.036|   0.000) D: [alsa-sink] sink.c: Processing rewind...
( 684.036|   0.000) D: [alsa-sink] sink.c: latency = 1337
( 684.036|   0.000) D: [alsa-sink] sink-input.c: Have to rewind 3320 bytes on render memblockq.
( 684.036|   0.000) D: [alsa-sink] source.c: Processing rewind...
( 696.234|  12.197) I: [alsa-sink] alsa-sink.c: Underrun!
( 696.234|   0.000) I: [alsa-sink] alsa-sink.c: Increasing wakeup watermark to 15.99 ms
( 702.033|   5.799) I: [alsa-sink] alsa-sink.c: Underrun!
( 702.033|   0.000) I: [alsa-sink] alsa-sink.c: Increasing minimal latency to 36.00 ms
( 702.033|   0.000) D: [alsa-sink] alsa-sink.c: Latency set to 36.00ms
( 702.033|   0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=59188
( 702.033|   0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15680
( 702.033|   0.000) D: [alsa-sink] alsa-sink.c: Latency set to 36.00ms
( 702.034|   0.000) D: [alsa-sink] alsa-sink.c: hwbuf_unused=59188
( 702.034|   0.000) D: [alsa-sink] alsa-sink.c: setting avail_min=15680
( 702.034|   0.000) D: [alsa-sink] protocol-native.c: Underrun on 'ALSA Playback', 0 bytes in queue.

...and it goes on.

The "Underrun!" messages alone happened a few times before, but it didn't skip.

I'd like to use PulseAudio, but it's pretty annoying having audio skip all the time.