"Shiftnav loading…" Doesn't disappear

Hi guys,

Since a few days I keep getting this message on the right bottom of my screen. At the same time my pictures and some other stuff doesn’t load anymore. When I click the popup I get another message that there is a problem with javascript. Seems like all plugins and my theme are up-to-date, so could you please help me out what to do now?
My site is http://www.motosurf.nl.

Thanks in advanced!