Started after 3.0.10RC update on one of my boards
SQL ERROR [ mysqli ]
Unknown column 't.topic_approved' in 'where clause' 
SELECT topic_id FROM phpbb_topics WHERE forum_id = 9 AND topic_last_post_time > 1322208430 AND topic_moved_id = 0 AND t.topic_approved = 1
Appears when guest visiting a forum with new topic mark as unread (Enable topic marking for guests: Yes). When guest choose to mark all forums as read, the error disappear. Logged in users never see this error.