Troubleshooting problem with submenus

First thank you folks for providing the best source of troubleshooting information. I've fixed pretty much every problem I had with the site I'm working on - except this one pertaining to the menus.

I have the color of the current top-level page set to maroon with white text.
I have the color of the parent of the current submenu page set to the same thing.
I have the submenus set to white with maroon text.

All the styling was done in the custom CSS plugin.

It all works except for one menu item "The Art Gallery". Visit http://www.stjathenaeum.org/WordPress and open any menu with the triangle. They all work except for the Art Gallery.

I've checked that the parent page is set correctly. I took those pages out of the menu and put them back into the menu. I even recreated the page for The Domes of the Yosemite.

Any assistance will be gratefully accepted. Please note that some of the content on the pages looks funky as the site is still in development.