Ho to kill locked programs...
I recently had a full-screen game stop responding. The mouse moved around fine so the system wasn't locked but I couldn't switch desktops, use ctrl+alt+esc, ctrl+z, ctrl+c, ctrl+esc, ctrl+alt+del, alt+f4, alt+tab or right-click. I had to power-cycle my box to get back to KDE.
How do you deal with a situation like that?