One thing to test might be to edit your /usr/share/X11/xkb/keycodes/evdev and see if changing this:
<I160> = 160; // #define KEY_COFFEE 152
to
<I120> = 160; // #define KEY_COFFEE 152
makes the Mute key actually mute the speaker (which works for me on my dell 1420)
Also, just to check the most obvious, can you attach your xorg.conf and the output of `setxkbmap -print`?
One thing to test might be to edit your /usr/share/ X11/xkb/ keycodes/ evdev and see if changing this:
<I160> = 160; // #define KEY_COFFEE 152
to
<I120> = 160; // #define KEY_COFFEE 152
makes the Mute key actually mute the speaker (which works for me on my dell 1420)
Also, just to check the most obvious, can you attach your xorg.conf and the output of `setxkbmap -print`?