If you want to enable Ctrl+Alt+Del to open System Monitor you have to do this:
Go to System->Preferences->Keyboard Shortcuts and search for “Logout” action (that is under Desktop actions) and you will see that Ctrl+Alt+Del combination is associated to Logout shortcut.
You have to click on that shortcut and press Backspace if you want to disable it or choose another combination.
Close this and open the Configuration Editor (if you have installed it you will find it under Applications->System Tools; or just run gconf-editor).
– On left tree select: apps->metacity
– Select “Global_keybindings” and search for a “run_command_X” value where X is between 1 and 12 and it is not used
– Add this value:
– Now select “Keybindings_commands” on left tree. Goto “command_X” where X is the same number selected in run_command_X option.
Add this value: gnome-system-monitor
Alternative solution (I prefer this one):
Run in terminal:
gconftool-2 -t str –set /apps/metacity/global_keybindings/run_command_1 “
gconftool-2 -t str –set /apps/metacity/keybinding_commands/command_1 “gnome-system-monitor”