I've had this happen probably 4 or 5 times since I got my Mac, and I can't figure out why it happens or what causes it... I use fast user switching and so I usually don't fully log out for days at a time. At times when I log back in, the "hover effects" don't work anymore. What I mean is when the pointer hovers over the dock, it doesn't react. When I click on a menu item and hover over the choices, they don't highlight. When I hover over a browser link, the cursor doesn't change into a hand. I can still select items on the dock, in menus, and hyperlinks... but it's strange not having the effects. I have to restart for everything to be normal again. I hope this explanation makes sense. Thanks for any help with this problem.