For some reason, whenever I press the Shift, Option, Control, or Command keys, their symbols appear in the center of the screen. It also appears that if I press one of them too many times, the key gets turned on permanently until I press it again. I'm on Leopard and have an Apple aluminum keyboard. Edit: I solved the problem by pressing the Shift key 5 times. I'm curious about what this is, though. It reminds me of StickyKeys on Windows.