Thanks , guys. It went back to normal (after all afternoon in the crazy mode) by itself, then came back again while I was reading your messages, which begs the question, am I doing something to make it go bonkers. As far as I can tell, it does it all by itself. The control button and spin of the wheel button worked but I think I'll go into preferences and turn off "zoom" permanently and hope that eliminates the seemingly random nutty and maddening episodes.