WordPress database error

When i publish a post, page or link I get this error message:
WordPress database error: [Unknown column ‘mt1.meta_key’ in ‘where clause’]
SELECT SQL_CALC_FOUND_ROWS wp_posts.ID FROM wp_posts INNER JOIN wp_postmeta ON (wp_posts.ID = wp_postmeta.post_id) WHERE 1=1 AND wp_posts.post_type = ‘sidebar’ AND (wp_posts.post_status = ‘publish’ OR wp_posts.post_status = ‘future’ OR wp_posts.post_status = ‘draft’ OR wp_posts.post_status = ‘pending’ OR wp_posts.post_status = ‘private’) AND ( (wp_postmeta.meta_key = ‘_cas_post_types’ AND CAST(wp_postmeta.meta_value AS CHAR) = ‘_cas_sub_simple_link’) AND mt1.meta_key = ‘_cas_post_types’ ) GROUP BY wp_posts.ID ORDER BY wp_posts.post_date DESC LIMIT 0, 1

If I then click back on the browser and try to publish it again, it works fine.
Do anyone know what the problem is and what I can do to fix it?