WordPress 3.5 broke the Arjun-X Theme. The developer is not supporting anymore, hence it was left to the user adopting the theme to fix it. Test and proved method is detailed in post by Samuel Wood (Otto) Tech Ninja post.
The Issue is with JQuery Custom File in the theme. WordPress 3.5 has included the correct copies of JQuery-UI, hence the custom file “jquery-ui-1.8.10.custom.min.js is not required hence delete it and ref to this file in “function.php” hs to edit to as follows
// comment this line
// wp_enqueue_script('arjunaJQueryMinJS', get_template_directory_uri() .'/lib/jquery-ui-1.8.10.custom.min.js');
// and add this line