Mouse button preferences are being silently dropped
Since discovering that my Mighty Mouse can function as a two-button mouse, I've been experimenting with other mouse preferences. I've set ‘Button 4’—squeezing (somewhat awkwardly, in my opinion) the two side buttons together at the same time—to ‘Exposé – Desktop’. This preference seems to randomly revert to plain old ‘Button 4’—that is, it does nothing. About once a day I have to reset it. Why would a system preference just fall off like that?