ThinkPad x200 mute key not registering

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http://crunchbang.org – It's probably not a hardware issue. I had the same symptoms you can fix it by editing the line GRUB_CMDLINE_LINUX="" in /etc/default/grub toGRUB_CMDLINE_LINUX="acpi_osi="Linux"" and then runningsudo update-grub then edit the Openbox rc.xml and add <keybind key="XF86AudioMute"> <action name="Execute"> <command>amixer -D pulse set Master toggle</command> </action> </keybind> under <keyboard>Restart your system and it should work perfectly (HowTos)