The cursor on my 10.8.2 iMac has started misbehaving. It changes from normal NW pointing arrow, to I-beam, to pointing finger, depending on where I move the cursor. Imagine the screen divided into 4 vertical stripes, numbered 1 to 4, left to right. With focus in the Finder, as I move the cursor into stripe #2, it changes from arrow to finger; when I move out to any other stripe, it goes back to an arrow. In applications Mail and Safari, the changes seem to happen at random, with no special relation to position. It's about evenly split between arrow and finger, with I-beam now and then. I use a Magic Mouse, but I get the same behavior with a wired USB mouse. I have not recently installed new hardware or software. The behavior started Saturday morning after my weekly restart. Today I performed a "safe" boot followed by another restart - no change. Then I booted to "recovery" and repaired permissions, twice. No change. Any advice?