do you have any sorting plugins installed?
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 = ‘post’ AND (wp_posts.post_status = ‘publish’) AND (wp_postmeta.meta_key = ‘preis’ ) GROUP BY wp_posts.ID ORDER BY wp_posts.menu_order, wp_postmeta.meta_value,wp_postmeta.meta_value+0 ASC LIMIT 0, 8
wp_posts.menu_order should not be here…
