I figured it out after all. It turns out that the menu buttons were finalized on one of the other pages which had only the plain powder blue background and then copied to the home page which has the boat image behind the buttons. Since the buttons themselves have a shadow effect, the effect was also copied and so overlayed the image.
By changing the shadow effect so that VSD can re-render the button in it's new position, it properly applied the effect and eliminated our problem.
The new problem is how to eliminate the momentary border around a button when it is clicked using FIREFOX only.


(sorry to morph the topic yet again, but thought it may be helpful to keep the context)