pulseaudio killing sound on Karmic

[Colin Law]

Hi
I have Ubuntu 9.10 installed on a Toshiba A100-197.  Sound was not
working and when looked at the devices in the pulseaudio volume
control all I saw was Dummy Output (or something similar).  When I
played something the output could be seen in the amplitude bars but no
sound was heard.

After a lot of googling and trying various things I discovered that if
I remove pulseaudio and use the alsa mixer directly it works ok, which
came as a surprise to me as up till then I had assumed that it was a
lower level problem.  When I install pulseaudio again the sound stops.
 I have fiddled with settings in pulseaudio to no avail.  Any
suggestions as to how to analyse or fix the problem?

aplay -l shows
card 0: Intel [HDA Intel], device 0: ALC861 Analog [ALC861 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 0: Intel [HDA Intel], device 6: Si3054 Modem [Si3054 Modem]
  Subdevices: 0/1
  Subdevice #0: subdevice #0

Colin