[Plugin: The Events Calendar] Getting 'Page not found' when searching through months

Whenever you select a month from the dropdown, the page redirects to ‘page not found’. For some strange reason, ‘undefined’ is appended to the url:

Here is what should happen:
http://powermepositive.com/pmpb/events/2012-07/

Here is what currently happens:
http://powermepositive.com/pmpb/events/undefined2012-07/

Can someone please assist me?

http://wordpress.org/extend/plugins/the-events-calendar/