I have a few mighty mouses around the house (3) one has a broken scroll wheel, one is perfectly functional, and another is still new in the box. when plugged into my Mac mini the all of them can trigger expose (squeeze) and dashboard (middle button) every time. right click works beautifully. however when i plug them into my MacBook and set it up for spaces (middle button) and expose (squeeze) - neither of the functions work. the primary, right click and scrolling all work beautifully. i can't find any other info about this online - most people just have broken mighty mouses. any thoughts? maybe a pref file i could trash?