When I first installed Ubuntu 9.04 the keyboard controls worked to mute/unmute and raise/lower volume. Now, after security updates, and the installation of various packages the keyboard shortcuts don't affect the Master volume control. The are still recognised in the keyboard shortcuts panel, but don't affect the volume control in the panel, even though they do pop up the semi transparent volume indicator. In the screen shot you can see that one of the volume indicators shows muted, but the other does not. Why are keyboard shortcuts no longer controlling the volume?