Upfront/Spirit drop down menu items not working

Hello,
I'm doing this site with Spirit/Upfront. It is my first Upfront.
http://test-mrt.dreamhosters.com

The top navigation menu has some drop downs. Only the first couple of items that drop down work. The menu disappears when I try to click on "Our Policies".

It looks like there could be a clash with the text block over the background picture with the charity name in white text.

Can you suggest a fix?

A possible workaround: I could put the nav menu in a subregion at the bottom of the picture, but I would need to change its behaviour so that submenus appear above the main menu when selected. Currently the menu would open down off the screen if I put it at the bottom.

Regards,
Morgan