MySQL 5.1 lost its connection during query

I'm using Solaris as my operating system and everytime  I execute my query in mysql server, it replies to me error. It says,  "Lost connection to MySQL server during query".  I'm using I am using mysql  5.1.  What can I do to get rid of this issue?

MY QUERY IS:

ELECT post_time, p.topic_id, t.topic_replies, post_id, u.user_id, username 
   FROM jforum_posts p, jforum_users u, jforum_topics t , jforum_forums f 
      WHERE t.forum_id = f.forum_id 
         AND t.topic_id = p.topic_id 
         AND f.forum_last_post_id = t.topic_last_post_id 
         AND t.topic_last_post_id = p.post_id 
         AND p.forum_id = 1 
         AND p.user_id = u.user_id 
         AND p.need_moderate = 0;