Since Wordpress upgraded to 4.0, my top menus no longer work.

Stupid WP...everytime it updates, it messes up something in my theme. Now the drop-down menus I have on all the pages of my website (centerforhistory.org) don't work. I am my own worse enemy and if I try to dig into this too far, I'll end up having to reinstall EVERYTHING on my WP site. That's why I've posted this question. Any clues? (I know you may have to use an admin account to see).