My Command + Z stopped working. In any app. Including keyboard viewer.
Neither Left nor Right Command.
It's not hardware – Command + Option + Z (or Command + any other modifier) works on both sides.
It's like something is 'trapping' that combo. What could it be? I quit Butler; that was the only shortcut app I had.
Strange … if I go to Keyboard Pref Panel > Shortcuts, and 'Add' an All Applications shortcut for Undo, then in that little window I can enter Command + Z. But it still does not work anywhere else!