I'm confused. I've had my iMac and Magic Mouse for several weeks now no issue. Suddenly today the mouse scroll direction reversed to the "unnatural" direction, i.e. its movements mimics the scroll bar rather than the page. The batteries were low so I swapped them...no difference. I then restarted the computer, and that fixed it. For a few minutes. Soon went back to the unnatural directions again.

Yes, I know I can with the scroll direction in system prefs, but that also reverses the way swipes work and I'm too used to the "right" way. Besides, that's just a workaround, there should be an explanation and a fix.