I only work one day a week and go into 6 class rooms to do my thing! Over the last two weeks, when I attach my laptop to the IWB the laptop screen goes black and I can only see the display on the big screen. Mostly I can manage, but today I wanted to freeze the screen on a ppt slide and then play a sound file and I couldn't. Tech support is never in when I am and am sure it must be something straightforward - please can someone give me some simple (idiot-proof) instructions? (Pretty please ).