Launchpad key not working. Anyone else?

Hi Support Forums.

I just picked up one of the new Airs, and I restored everything from a Time Machine backup (of a computer that was running Lion GM). I'm having trouble with the Launchpad function key (F4). All of the rest of the function keys do their jobs properly, but the Launcpad one doesn't start up Launchpad.

I tried assigning a keyboard shortcut to Fn+(F4) and that worked properly, so it's not an issue with the hardware. And on the guest account, the key works properly, so it's specific to my user account.

I searched the forums, and I couldn't find anything about specific function keys going out. Does anybody have an ideas on what I can do to restore the key? Is there a plist that I can edit or delete? Is anyone else experiencing this?