Sound Settings is missing all output devices [duplicate]

Possible Duplicate:
My sound stopped working today, how can I fix it?

I'm baffled by this discrepancy:

1. This speaker test is successful:

   speaker-test -c 6 -D 'surround51:CARD=PCH,DEV=0'
   

2. Sound Settings is behaving as if I have no sound card:

   

How do I find out what's causing this problem?

Details

Have a look at aplay -L, pacmd list-cards, lshw, pulseaudio -vvvv, and pavucontrol. I do not use HDMI.

This discussion of a similar problem on a PulseAudio mailing list suggests that changes to /etc/pulse/default.pa might be responsible, but I have not edited this file.

Turns out I was running into Bug #590780: Installing "randomsound" package causes Pulseaudio to stop functioning at reboot and didn't know it yet. See this answer:

1. Run pstree | less
2. In that, type /arecord and press return to find the arecord process.
3. Press up once and you'll see its parent. In my case this was randomsound.