I pressed the camera icon, the iris blades of the camera appeared as normal but they never opened up to reveal an image. The whole Ipad was frozen.
Holding the power off did nothing, I had to resort to holding the Home button and the Power switch together to make the Apple icon appear. It then sat for a long time - 2 or 3 minutes and then the power on bar appeared. ok now.
I have the latest updates on this machine.