Menu drop downs not always visible

Hi All,

any help would be much appreciated!

I’m working on a site for the London Games Festival and I’m finding with the navigation sometimes the drop downs aren’t always visible when you roll over them. After a while they do display after you have rolled over it enough, but then when you click on a new page, it starts over again.

Please help 🙂

http://games.london/#home

https://wordpress.org/plugins/widgetize-navigation-menu/