System Crash

SELECT p.id AS PAGE ,p.purl ,c.id as comment_id, c.* ,t.* ,cu.username AS commentor ,cu.id FROM et_comments c JOIN et_page p ON p.purl = c.threadhead LEFT JOIN et_comment_threads t ON t.id = c.threadid JOIN et_user cu ON cu.id=c.userid WHERE c.deleted != 1 GROUP BY p.id ORDER BY t.tlastpostid DESC, c.created LIMIT 100