Navigation bar overlaying slideshow - z-index issue?

Can someone please help me with a problem having to do with a navigation bar that is overlaying a slideshow? Here is the URL:

http://www.humanities.uci.edu/els/french/awards2.php

I have tried eliminating all the z-index references from the menu bar CSS, but the problem persists. I have no idea what to try next. Any help or suggestions are very much appreciated.

Thank much!