Mac OS X, mouse moves but mouse clicking and keyboard stroke doesn't respond?

Do you have any wireless keyboards/mice in the room connected to a different mac? If so turn them off. I had this happen. Working on iMac OSX with wireless keyboard & mouse, I could move mouse pointer, but the click would not work and the keyboard would not work. I had a MacBook pro in the cupboard with a wireless mouse that was still switched on. This was the problem. As soon as I turned this other wireless mouse off, my keyboard and mouse responded perfectly.