Page layout changing

I’ve just installed the calendar at http://www.mgccyregister.com/wp/y-type-news/events-calendar/ and it works fine in Agenda view, but when I click on Read More for an event, the page layout changes. It introduces a sidebar, which the website doesn’t have, and enables comments which are turned off in the site.

Does anyone know what might be causing this?

I’ve recently installed the calendar in another club website at http://www.mgabingdon.co.uk/wp/events/ and I’ve had no problems with it, in fact it’s a brilliant calendar, the best I’ve seen for WordPress!

http://wordpress.org/extend/plugins/all-in-one-event-calendar/