Error when starting to use...

I get the following error when selecting one of the main options to start using this plugin when I clicked on Display post types on "Home":

Warning: Illegal offset type in isset or empty in .../beachheadcommunications.com/wp-includes/post.php on line 828

Warning: Illegal offset type in isset or empty in .../beachheadcommunications.com/wp-includes/post.php on line 828

Warning: Cannot modify header information - headers already sent by (output started at .../beachheadcommunications.com/wp-includes/post.php:828) in .../beachheadcommunications.com/wp-includes/functions.php on line 861

Warning: Cannot modify header information - headers already sent by (output started at .../beachheadcommunications.com/wp-includes/post.php:828) in .../beachheadcommunications.com/wp-includes/functions.php on line 862