Fatal Error Upon Activating Buddypress

I got this error:
Fatal error: Cannot redeclare bp_dtheme_ajax_querystring() (previously declared in /home/pintpix1/public_html/thedentaldegree.com/wp-content/themes/bp-fun/_inc/ajax.php:17) in /home/pintpix1/public_html/thedentaldegree.com/wp-content/plugins/buddypress/bp-themes/bp-default/_inc/ajax.php on line 81

How do I fix?

Site: http://thedentaldegree.com/

thanks