Coursepress Pro Warning Messages

Hi,

I have coursepress pro installed and am having a few issues.

First, I deleted the sample course that came in the plugin, but when I go to "preview" mode in the course I am creating, I still see elements from the deleted course.

Secondly, I get the following warnings in preview mode and also if I enter the course (course is in draft mode at the moment).

Warning: array_key_exists(): The first argument should be either a string or an integer in /home/kerric/public_html/wp-includes/cache.php on line 669

Warning: Creating default object from empty value in /home/kerric/public_html/wp-content/plugins/coursepress/includes/classes/class.shortcodes.php on line 2955

Warning: array_key_exists(): The first argument should be either a string or an integer in /home/kerric/public_html/wp-includes/cache.php on line 669

I have a membership site plugin and I deactivated that to see if it was maybe interfering but that made no difference.

Any ideas?