DB error?

[AWMJen]

Database error in vBulletin 3.7.0 Beta 6:

Invalid SQL:

			SELECT IF(votenum >= 1, votenum, 0) AS votenum, IF(votenum >= 1 AND votenum != 0, votetotal / votenum, 0) AS voteavg, votetotal, thread.threadid, thread.title, thread.replycount, postusername, postuserid, thread.dateline AS postdateline, IF(views <= thread.replycount, thread.replycount+1, views) AS views, thread.lastposter, thread.lastpost, thread.lastpostid, pollid, thread.forumid, thread.open, sticky
			, NOT ISNULL(subscribethread.subscribethreadid) AS subscribed, thread.iconid AS threadiconid, iconpath AS threadiconpath, post.pagetext AS preview, threadread.readtime AS threadread, forumread.readtime AS forumread, thread.attach
			FROM vb_thread as thread
			 LEFT JOIN vb_subscribethread AS subscribethread ON (subscribethread.threadid = thread.threadid AND subscribethread.userid = 184) LEFT JOIN vb_icon AS icon ON (icon.iconid = thread.iconid) LEFT JOIN vb_post AS post ON (post.postid = thread.firstpostid) LEFT JOIN vb_threadread AS threadread ON (threadread.threadid = thread.threadid AND threadread.userid = 184)
				LEFT JOIN vb_forumread AS forumread ON (thread.forumid = forumread.forumid AND forumread.userid = 184)
			WHERE open != 10
				AND thread.visible = 1 AND thread.lastpost > 1206286375
				 AND (thread.forumid IN(11,16,15,10,42,13,28,49,17,18,23,24,19,25,50,21,20,40,45,47,30,41,31))
			ORDER BY lastpost DESC
			LIMIT 5;

MySQL Error   : MySQL server has gone away
Error Number  : 2006
Date          : Tuesday, April 22nd 2008 @ 08:33:26 AM
Script        : http://*******.com/
Referrer      : 
IP Address    : 
Username      : 
Classname     : vb_database
MySQL Version :

Server has 'gone away'..........?? What the heck is that about?