Just got a new iMAC so I'm a bit rusty. It comes with a magic mouse which has a touch screen thingy on the top surface. It's supposed to do the divil-an'-all but it's driving me nuts On a spread sheet or web page the cursor moves far right at the slightest touch or the screen shot becomes magnified to the extreme. If I tap the mouse surface it SOMETIMES returns to normal. Why is this happening? Is it the closeness of my fingers to the mouse or is there a preference setting somewhere. My Missing Manual has missed this quirk.