Hi All Sorry, lost as in the brightness funtionality does not work anymore but the keys themselves are working as normal function keys OK. After proving my monitor (24inch LED ACD) and cables are OK I have come here to post the problem. Has anybody else had this problem arise since updating to SL on their Mac Pro or after doing any of the updates ? My other machines have been updated and they are OK. (20inch iMac/13inch Alu Laptop. I cannot place when the problem started because I have using a Samsung monitor over the past weeks. All cables are connected as they should be.