Got a link to your site so we can take a closer look?
The dynamic drive menus work fine for me in FF, IE6, IE7, and IE8. Without seeing a URL to your page, it's impossible to know what if anything you've done differently.
Thanks for the replies/clarifcation, all. Here is a link to my page: http://phoenixcorporatephotography.com/aerial-photography.html
The thumbnails on the left are controlled by jQuery and are supposed to slide left off the page when not active. It worked before I added the nav menu.
Thanks for taking a look!