include($phpbb_root_path . 'includes/constants.'.$phpEx);
include($phpbb_root_path . 'includes/template.'.$phpEx);
include($phpbb_root_path . 'includes/sessions.'.$phpEx);


into:

include($phpbb_root_path . 'includes/constants.'.$phpEx);
if (!class_exists('template'))
{
	include($phpbb_root_path . 'includes/template.'.$phpEx);
}
include($phpbb_root_path . 'includes/sessions.'.$phpEx);