Upgrade to Hardy, can't raise/lower/mute volume

[James Cummings]

Hiya,

I've just upgraded one of my machines to Ubuntu 8.04 and something
seems to be wrong with the sound.  Needless to say it was working fine
before, but now I get sound, but I'm unable to control it, i.e. I'm
unable to raise/lower or mute it.  I.e. if I open volume control and
try to lower the volume bars they just jump back up to the top.  This
is fairly important for this machine because it also acts as a mythtv
frontend.

The output of "alsamixer":

alsamixer: function snd_mixer_load failed: No such file or directory

and "lsmod |grep snd":

~$ lsmod |grep snd
snd_hda_intel         344728  0
snd_pcm_oss            42144  0
snd_mixer_oss          17920  1 snd_pcm_oss
snd_pcm                78596  2 snd_hda_intel,snd_pcm_oss
snd_page_alloc         11400  2 snd_hda_intel,snd_pcm
snd_hwdep              10500  1 snd_hda_intel
snd_seq_dummy           4868  0
snd_seq_oss            35584  0
snd_seq_midi            9376  0
snd_rawmidi            25760  1 snd_seq_midi
snd_seq_midi_event      8320  2 snd_seq_oss,snd_seq_midi
snd_seq                54224  6
snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_seq_midi_event
snd_timer              24836  2 snd_pcm,snd_seq
snd_seq_device          9612  5
snd_seq_dummy,snd_seq_oss,snd_seq_midi,snd_rawmidi,snd_seq
snd                    56996  11
snd_hda_intel,snd_pcm_oss,snd_mixer_oss,snd_pcm,snd_hwdep,snd_seq_dummy,snd_seq_oss,snd_rawmidi,snd_seq,snd_timer,snd_seq_device
soundcore               8800  1 snd


And "$ lspci |grep Audio" is:

00:10.1 Audio device: nVidia Corporation MCP51 High Definition Audio (rev a2)

and output of  "$ aplay -l" is:
**** List of PLAYBACK Hardware Devices ****
card 0: NVidia [HDA NVidia], device 0: ALC861 Analog [ALC861 Analog]
 Subdevices: 1/1
 Subdevice #0: subdevice #0

Just in case any of that helps.

Any suggestions appreciated!

-James