F12: Another Pulseaudio "No Sound" problem

[Don Levey]

I've been reading with interest the problems with PulseAudio since F12 
came out, and I find myself in a similar situation (none of the 
previously offered solutions seem to have helped).

First, the vitals:
Dell Dimension E521
Athlon 64 X2 3800+
Running KDE 4.3.5

Running F12 2.6.31.12-174.2.22.fc12.x86_64, fully updated as of this 
moment (according to yum).
[don at dauphin ~]$ rpm -qa | grep pulse
pulseaudio-libs-glib2-0.9.21-4.fc12.x86_64
pulseaudio-module-gconf-0.9.21-4.fc12.x86_64
pulseaudio-libs-0.9.21-4.fc12.x86_64
pulseaudio-module-x11-0.9.21-4.fc12.x86_64
alsa-plugins-pulseaudio-1.0.22-1.fc12.i686
kde-settings-pulseaudio-4.3-16.1.noarch
pulseaudio-module-bluetooth-0.9.21-4.fc12.x86_64
pulseaudio-module-jack-0.9.21-4.fc12.x86_64
pulseaudio-libs-0.9.21-4.fc12.i686
alsa-plugins-pulseaudio-1.0.22-1.fc12.x86_64
pulseaudio-gdm-hooks-0.9.21-4.fc12.x86_64
pulseaudio-libs-glib2-0.9.21-4.fc12.i686
pulseaudio-utils-0.9.21-4.fc12.x86_64
pulseaudio-0.9.21-4.fc12.x86_64

[don at dauphin ~]$ lsmod | grep snd
snd_hda_codec_idt      66816  1
snd_hda_intel          30360  2
snd_hda_codec          72832  2 snd_hda_codec_idt,snd_hda_intel
snd_hwdep               9224  1 snd_hda_codec
snd_seq                58080  0
snd_seq_device          7620  1 snd_seq
snd_pcm                83144  2 snd_hda_intel,snd_hda_codec
snd_timer              22608  2 snd_seq,snd_pcm
snd                    67592  12 
snd_hda_codec_idt,snd_hda_intel,snd_hda_codec,snd_hwdep,snd_seq,snd_seq_device,snd_pcm,snd_timer
soundcore               7328  1 snd
snd_page_alloc          9568  2 snd_hda_intel,snd_pcm

[don at dauphin ~]$ lspci | grep Audio
00:10.1 Audio device: nVidia Corporation MCP51 High Definition Audio 
(rev a2)

[don at dauphin ~]$ cat /proc/asound/cards
  0 [NVidia         ]: HDA-Intel - HDA NVidia
                       HDA NVidia at 0xfe024000 irq 23


It seems that I am able to get sound for about 30 seconds; it starts, 
but slowly fades over that time to nothing.  Restarting/relogging in 
sometimes resets it, but not always.

Any suggestions as to what I can try, or what additional information I 
can post that might help to diagnose this?  I'm at a loss.

Thanks in advance,
  -Don Levey