Sounds works for uid=1000, but not for the main user on the system, running with uid=1003. Upon boot, the Ubuntu chime clearly plays. When the user is logged in, sound test shows no input device.
I looked at several of the previous questions, added the user to audio, video, pulse, pulse-access — but still no luck.
To recap: This worked perfectly in 11.04, 11.10, 12.04. It works for the default user uid=1000, it does not work for the actual user. The differing group memberships are mainly for adm, admin, sudo and the like.
Edit: Some exploring confirms that it is local to the user and machine; on a second box it works fine. So somewhere below
~/.gconf/ a toggle must have been flipped. And yes, reset
alsamixer, reset mute button — all to no avail.