CodyRo on "[Plugin: HC Custom WP-Admin URL] Error"

I take this error when i try to acces my slug:

Fatal error: Cannot redeclare get_file_description() (previously declared in /home/USERNAME/public_html/wp-admin/includes/file.php:58) in /home/USERNAME/public_html/wp-admin/includes/file.php on line 71

http://wordpress.org/plugins/hc-custom-wp-admin-url/