I had some problems with the sound after installing Jaunty on my old computer. I followed a lot of instructions from bugs reports, from forums, and nothing worked. I could have sound in Totem with the OSS mixer, but not Alsa. The rest was not working: Firefox, Flash, VLC, none of them deliverd any sound. All the parameters seemed fine with Alsa, but I couln't get any sound with it. Weirdly, alsamixer wouln't run because it couln't find any device and Pulseaudio couln't recognize my nForce 2 sound chip. I though it had to do with the hardware and the drivers.

And then by accident, I noticed that when logged in other sessions than mine, everything worked fine, with the same parameters. So it got me thinking and I figured it out: I had that user account on that machine for a very long time. And every time I was upgrading Ubuntu, I was keeping the old files in /home/myname. So versions after versions, sound drivers files added up, but not nicely. So I did some cleaning, removing option folders from software that hasn't been installed in years on my machine and moved everything remotely related to Gnome or Alsa. Then I logged in: BAM! Everything was working again!