The same bug affected my Karmic Koala. Sound is turned off. It's happened after upgrading Alsa → alsa-base (1.0.20+dfsg-1ubuntu5) to 1.0.22.1+dfsg-0ubuntu3~ricotz1; and pulseaudio → pulseaudio (1:0.9.19-0ubuntu4.1) to 1:0.9.22~0.9.21+stable-queue-32-g8478-0ubuntu11~~karmic~ubuntuaudiodev1).
My kernel is : 2.6.32-15-generic.
Then I tried to downgrade to the previous version, but the sound hasn't returned.
The same bug affected my Karmic Koala. Sound is turned off. It's happened after upgrading Alsa → alsa-base (1.0.20+ dfsg-1ubuntu5) to 1.0.22. 1+dfsg- 0ubuntu3~ ricotz1; and pulseaudio → pulseaudio (1:0.9. 19-0ubuntu4. 1) to 1:0.9.22~ 0.9.21+ stable- queue-32- g8478-0ubuntu11 ~~karmic~ ubuntuaudiodev1 ).
My kernel is : 2.6.32-15-generic.
Then I tried to downgrade to the previous version, but the sound hasn't returned.