i got error like Xander, too.
i can see this below, too.
<input name=”referredby” type=”hidden” id=”referredby” value=”<div id=’error’>
<p class=’wpdberror’>WordPress database 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 ‘) ORDER BY post_id, meta_key’ at line 1]
SELECT post_id, meta_key, meta_value FROM wp_postmeta WHERE post_id IN() ORDER BY post_id, meta_key
</div>redo” />