The class Fx.Slide , which was the problem initially stated, is part of the mootools-more.js library.
That library was missing from your page, therefore I have used jQuery Easy to add that library manually.
The issue is gone and your menus now seem to work as expected but I have not checked all of the checking pages of your site.
Note that the path is hardcoded into the jQuery Easy plugin and once you go live you will need to adjust the path (see the 'add scripts' section of the 'advanced' tab).
I have setup the plugin properly to just affect the checking part of the site. Other parts of the site should have a different treatment, since you have duplicates of libraries all over. But this is only possible to do with jQuery Easy Profiles.
Simplify Your Web is not affiliated with or endorsed by The Joomla! Project™ or Open Source Matters. The Joomla!® name and logo is used under a limited license granted by Open Source Matters the trademark holder in the United States and other countries.