Fireworks seems to think that I have overlapping rectangles when I don't. In this case, I have two rows of navigation links made with HTML symbols. Each row has one rectangle behind the text links. There are no other rectangles, visible or hidden. Nevertheless, Fireworks says "Objects 'navbar_2_box' and 'home_btn' boundaries overlap, switching to absolute positioning mode."
Why does this happen? I have seen this error in other pages also, where there were definitely NOT any overlapping objects.
Any chance that you have added a drop shadow or glow to the button shapes?