I have Lenovo X200s and I have been using Ubuntu on it for several years now, it is running Ubuntu 12.04 since it was released in April 2012. Everything was fine until a week or so ago volume buttons stopped working correctly. I think that this error appeared after I ran updates for Precise, but I am not sure. Previously I was able to adjust sound output volume and Ubuntu was showing the output volume change on upper right corner, under the sound icon, everything was working fine.
The behavior I am getting now is:
Mute button works as expected - it turns off any sound. Pressing any of volume buttons actually turns the sound on, but the volume will not change as I press any of those buttons repeatedly. Pressing mute button and any of volume-up or volume-down buttons will turn the sound on and off, which means that physical buttons are working correctly.
When I turn the sound on and I hear the sound of some youtube videos or whatever, the sound volume icon on top right corner of the screen still shows as if it was muted and it does not allow me to adjust the volume with that slider.
