It looks like in X.org Server > 1.6.0, they disabled zapping the X server (Ctrl+Alt+Backspace to kill X). This really annoyed me as I often restart the X this way. Anyways this has been noted in the Arch Wiki entry for Xorg. A quick fix to this would be to add this line to your .xinitrc:
setxkbmap -option terminate:ctrl_alt_bksp
Second I thought I would mention one of the most useful mpc commands that most people don’t even know about. Instead of doing just “mpc update” to update the entire library (waste of time for small changes) you can follow that with a folder in your music directory to update only that folder. Say I just added a new album to my Joy Division folder. I’d just do:
% mpc update Joy\ Division
And the MPD library is updated with only changes to the Joy Division folder. Just don’t forget to escape spaces and other characters. I use this all the time when making small changes. This can also be very useful for playing files external to your MPD directory with systemlinks just like mpc-play does.