Not all Wordpress pages are displaying menus correctly

Not all Wordpress pages are displaying menus correctly

I am having a specific issue with my wordpress site that I'm trying to
resolve.
The site is at www.dontforgetthebubbles.com
As you will see the homepage looks fine.
But many posts are not displaying correctly. As an example:
http://www.dontforgetthebubbles.com/2013/08/cradle-cap/#
The menu columns are all showing simultaneously (hover over 'Clinical' and
compare this to the home page to see what I mean)
The 'toggle' button is not working (see
http://www.dontforgetthebubbles.com/2013/07/intubating-with-stridor/ for
an example of a post where it does work correctly).
I think the issues are related to more recent posts (and the older posts
are ok) but it is affecting around 15 posts.
Could anyone suggest what my be causing this?
Thanks