Layering problem between GoLive and Menu Machine

I have a grid of thumbnail images on my HTML page. When you click on an image, the background fades and a larger version of that chosen image pops up for better viewing. However, it pops up BEHIND the horizontal Menu Machine links. This menu bar stretches across the top of the page just under the main banner.

How can I fix it so the inflated image isn't obscured by the menu bar?