database error

[wolfyman]

I get a few erors a day from vbulletin, but I have no idea what they are from. Usually they say this:

Database error in vBulletin :

Link-ID == false, connect failed
mysql error:

mysql error number: 0

But today I got a different one, what's this mean?

Database error in vBulletin 3.0.7:

Invalid SQL:
SELECT filename, attachment.postid, attachment.userid, attachmentid,
attachment.dateline, SUBSTRING(filedata, 1, 2097152) AS filedata, filesize,
attachment.visible, mimetype, NOT ISNULL(deletionlog.primaryid) AS isdeleted,
thread.forumid, forum.password, thread.threadid
FROM attachment AS attachment
LEFT JOIN attachmenttype AS attachmenttype ON(attachmenttype.extension = SUBSTRING_INDEX(attachment.filename, '.', -1))
LEFT JOIN deletionlog AS deletionlog ON(attachment.postid = deletionlog.primaryid AND type = 'post')
LEFT JOIN post AS post ON (post.postid = attachment.postid)
LEFT JOIN thread AS thread ON (post.threadid = thread.threadid)
LEFT JOIN forum AS forum ON (forum.forumid = thread.forumid)
WHERE attachmentid = 410

mysql error: MySQL server has gone away

mysql error number: 2006

MYSQL server has gone away?!! Any ideas?