Fluxbox
From Indie IT Wiki
Disable CTRL+ALT+DEL To Quit / Kill Fluxbox X Server
Add the following lines to your /etc/X11/xorg.conf file...
Section "ServerFlags" Option "DontZap" "true" EndSection
Comment out the following lines in your ~/.fluxbox/keys file...
# exit fluxbox # Control Mod1 Delete :Exit