I'm running Word 2010 on Windows 7 64-bit.
Often (though not always), when I edit text a mini-toolbar appears in the margin. (I've disabled mini-toolbars in Word options.) I've included a screen capture.
The two options (undo automatic emphasis and Stop formatting beginnings of lists) have nothing to do with the text I'm working on.
If I click the third option (Control AutoFormat options), Word crashes (and takes a very long time to shut down).
The behavior is mostly annoying, but whenever the mini-toolbar appears I get nervous about the stability of Word and of the document I'm working on.