I still don't see the behavior that you are seeing. If I revert to the default arrow and then move the hotspot to the bottom-left corner, apply changes, and click in the desktop, the selection begins below and to the left, just as expected.
Question - if you move the hotspot, hit Test Cursor, and then click around within the Mighty Mouse prefpane, without clicking anywhere else first, has the hotspot moved? Another question - if you apply a custom cursor set, log out, and log in, is the custom cursor applied?
I'm assuming at this point that this problem isn't widespread, that it's limited to just you. So you might want to move to email instead. My name is Jason, and the company is the one you got Mighty Mouse from. You can probably guess the correct email address from there.
