Split from this thread.
This is happening to me too recently. It happens every time I go to copy text in Word. It appears right after I right click and select copy. It is really annoying. I thought it might be a phish so I just delete it. It sounds like a problem with a recent update now though. The screen shot elsewhere in this discussion is exactly what I see. Of note I copied this to paste elsewhere and the message did not appear so it might be restricted to Office.