Periodically the keyboard on our MK320 combo will either stutter or not respond at all. It has fresh batteries. What happens is as one enters numbers from the keypad or characters from the keyboard the not display on the screen for sever seconds and then they "spray" across. Or they don't appear at all. We've never had a Logitech product display this kind of weird behaviour. Any idea what's going on? We're running Windows 7 Home Premium.