Daily Theme - issues with IE7?

Hi there - I've just finished putting together this great site with Daily theme and got the following notice from the government office that has to "approve" the site:

"The menu you are using does not function well in Internet Explorer 7, which is used in the our network. The drop-down from the top row of the menu displays behind the bottom row. This may be fixable by adjusting the z-index of the layers. If not, you will need to find a new place to display the bottom menu row."

I know WPMU DEV's themes are compatible with all browsers, and I had done a browser check, but it only gave me screenshots. Can you advise on what I should do? I haven't done anything to the design of the menus.