Actually there may be a separate banner window opened up that you're not supposed to see.
Once I found a window opened and placed just so it would be outside my 1600x1200
resolution desktop, but, a tiny slice of the browser's left side appeared at my bottom right desktop side.
I managed to grab it and move it to the middle and saw that it was
a separate flash ad originating from wincustomize.com.
Go figure.