Comment 5 for bug 67998

To anyone else having this problem, the solution described by Jeffrey, above, worked for me. I was having trouble starting esd back up. Not having esd running meant I could only play sounds from one source at a time (I had to close Rhythmbox if I wanted to hear anything else!).

Here's what I did:
  chris@chris-desktop:~$ asoundconf list
  Names of available sound cards:
  M5455
  M44
  chris@chris-desktop:~$ asoundconf set-default-card M5455
  chris@chris-desktop:~$ esd &

I'd second Stefan in saying that it seems this problem should be given more attention. I'd imagine there are several users [who've upgraded from Dapper to Edgy] that are left with a half-working sound configuration.