All of a sudden (maybe after my last update manager run) the volume control icon in the system task bar is missing and is replaced with a "folder" icon. Hovering the mouse cursor over it shows the message "mixer cannot be found". However clicking on the icon does bring up the mixer, and the controls work. I also have a volume control applet in Cairo-Dock, and it has stopped functioning, IE: it LOOKS like it works howerver changing the volume setting in Cario-Dock makes no change in the volume.
How do I fix this???? BTW I'm running Mint 13 KDE 64 bit.