I just got one of these keyboards to replace my wired keyboard that stopped functioning on my 2.4 24 inch iMac. When I set up the keyboard in Logitech Control Center (version 3.3) I cannot get the brightness decrease key to work. It appears any key I configure to brightness decrease does not decrease the brightness and instead executes the show desktop command. Is this a quirk with the software or a quirk with the keyboard? I'm trying to decide if I should exchange it.