Getting errors after updating a custom post type

I have the plugin installed (and love it) but found today that when updating a custom post type, I get the following errors. These appear on the page after I click the update button, though the post does update.

This plugin is not setup for the post type either.

Warning: mb_regex_encoding() [function.mb-regex-encoding]: Unknown encoding "" in /home/totallys/public_html/XXXX.com/wp-content/plugins/yet-another-related-posts-plugin/keywords.php on line 13

Warning: mb_strtolower() [function.mb-strtolower]: Unknown encoding "" in /home/totallys/public_html/XXXX.com/wp-content/plugins/yet-another-related-posts-plugin/keywords.php on line 14

Warning: mb_regex_encoding() [function.mb-regex-encoding]: Unknown encoding "" in /home/totallys/public_html/XXXX.com/wp-content/plugins/yet-another-related-posts-plugin/keywords.php on line 13

Warning: mb_strtolower() [function.mb-strtolower]: Unknown encoding "" in /home/totallys/public_html/XXXX.com/wp-content/plugins/yet-another-related-posts-plugin/keywords.php on line 14

Warning: mb_regex_encoding() [function.mb-regex-encoding]: Unknown encoding "" in /home/totallys/public_html/XXXX.com/wp-content/plugins/yet-another-related-posts-plugin/keywords.php on line 13

Warning: mb_strtolower() [function.mb-strtolower]: Unknown encoding "" in /home/totallys/public_html/XXXX.com/wp-content/plugins/yet-another-related-posts-plugin/keywords.php on line 14

Warning: Cannot modify header information - headers already sent by (output started at /home/totallys/public_html/XXXX.com/wp-content/plugins/yet-another-related-posts-plugin/keywords.php:13) in /home/totallys/public_html/XXXX.com/wp-includes/pluggable.php on line 934

Any help would be appreciated, thanks!