I set up the sleep timer on 12" PB via Energy Saver (1.5 hours after non use). Somehow it is not going to sleep by itself (but the screen goes to sleep though according to Energy Saver setting). I can put it to sleep from menu. It is set up in the clam shell mode with a 20" ACD. This PB used to go to sleep according to Energy Saver setting; but, somehow it stopped following that setting. Can anyone suggest the fix for this?