CSS menu appearing behind javascript slideshow

I'm in the process of building a new page and am finding my stu nicols css drop menu is now appearing behind a new javascipt slideshow that I've added to the page. (here (http://www.ghostrecon.net/temp2.html))

I've checked the style sheet for the menu and it has a z-index set to 500, so it should be appearing on top...?

Anyone any ideas how to resolve this?

Thanks in advance.

The menu is on top for me in FF2 and IE6