I recently found that Mega menu submenus are not shown after the Jetpack 1.7 update. I experimented and this happens when I just make Jetpack connection with WordPress.com. If I just install Jetpack and if don't connect it with WordPress, Mega menu works correctly. This update also disables vSlider sliding images. Strange, but there are no jQuery errors on Firebug.
The site is http://www.reksas.lt. Maybe someone has any ideas what to do ?