What I usually do is remove pulseaudio and it works afterwards.
That's what I did, too. Removing pulseaudio instantly brings back the sound :-) Unfortunately pulseaudio is a dependency of gnome(3)-core , which is, as far as I understand, just for keeping gnome consistant.
I removed it, too. So I'll have to keep an eye on gnome for myself... (In fact I'm using KDE) Ingo