Well, I figured out what was causing the problem.. if it can help anyone. in my case, it was Microsoft Live Messenger. I just closed it and restarted it and the squares disappeared. I'm not sure if it is just Live Messenger or if it's because it is combined with "Messenger Plus!".
same problem here... it is also in the center, but when I click on it just right, I can actually move it and it creates another one, leaving the original in the center. weird. did you end up finding a solution for this?