منتدى استراحات زايد

I recevied this error 3 time at the day

PHP Code:
Database error in vBulletin 4.2.0:

Invalid SQL:

SELECT post.*,userfield.*, usertextfield.*, user.*, IF(displaygroupid=0, user.usergroupid, displaygroupid) AS displaygroupid,avatar.avatarpath, NOT ISNULL(customavatar.userid) AS hascustomavatar,
customavatar.dateline AS avatardateline, customavatar.width AS width, customavatar.height AS height,
customavatar.height_thumb AS height_thumb, customavatar.width_thumb AS width_thumb, customavatar.filedata_thumb
FROM post AS post
LEFT JOIN user AS user ON (user.userid = post.userid)
LEFT JOIN userfield AS userfield ON (user.userid = userfield.userid)
LEFT JOIN usertextfield AS usertextfield ON (user.userid = usertextfield.userid)
LEFT JOIN avatar AS avatar ON (avatar.avatarid = user.avatarid)
LEFT JOIN customavatar AS customavatar ON (customavatar.userid = post.userid)
WHERE post.postid IN (.,.,.,.,.,.);

MySQL Error : You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '.,.,.,.,.)' at line 10
Error Number : 1064
Request Date : Thursday, November 22nd 2012 @ 03:39:13 PM
Error Date : Thursday, November 22nd 2012 @ 03:39:13 PM
Script : http://www.mysite.com/vb/search.php?searchid=415575
Referrer : http://www.mysite.com/vb/search.php?do=process
IP Address : 41.254.2.247
Username : username
Classname : vB_Database
MySQL Version :

how to know from where the problem
and how to solve it

thanks