I have a new iMac 27 with retina for about three weeks now and have had intermittent keyboard issues. The issue is that at times the wireless keyboard is slow to respond with a delay between typed characters and what shows up on the screen. Often there are strange characters which show up almost as if the keyboard was trying to show a different language. The only language which is set up is US English. To resolve this I have to remove the batteries from the keyboard and then restart it or re-boot the mac...has anyone seen or solved this???