[Plugin: Event Registration] Features not working / Breaks other plugin(s)

It breaks the accordion functions of TheThe Tabs and Accordions. In fact, even if TheThe Tabs and Accordions, the accordion feature of Event Registration still doesn’t work. It also displays the full description in the calendar, not merely the course name. When clicking on a course title on the registration page, it doesn’t open in a modal window, but jumps to the next course title (or the end of the page if it is that last course).

http://wordpress.org/extend/plugins/event-registration/