Joomla! 3 uses the jQuery JavaScript library (replacing the MooTools library used in Joomla! 1 and 2). However jQuery has many optional plug-ins that can be added to the core files and Joomla! only installs some of them that it needs. As a result many templates and components - including ChronoForms v5 - load their own version of the jQuery files. This can cause confusion and conflict.
The simplest resolution I have found is to use the jQueryEasy extension from Simplify Your Web. This plug-in allows you to specify exactly which versions of jQuery and jQuery UI you want to use (usually the most recent full release is good) and where it should be downloaded from (usually the default Google Code setting is good). It will then check for any other versions being installed and block them so there is only one version loaded in the page.
Please see their site for the full documentation and options.
