Command+Z stopped working in all applications 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.

Update

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!
Whew! Found it!
It was an errant hotkey in Synergy.

Had to go through every running app one by one and look for hot key settings.