The Turnitintool plugin uses jQuery to display & refresh the submissions inbox. Unfortunately instead of just calling jQuery, it extends the jQuery object. If another copy of jQuery is loaded after this (e.g. by a plugin that displays graphic slideshows) will cause the overloaded instance of jQuery to be overwritten in the DOM, and Turnitin's functions will disappear.
I suggest that Turnitin rewrite their Javascript, to call jQuery as a client, instead of embedding their code into the library object.