Database error after changing directories

After I moved blog from mysite.com/blog to parent directory (mysite.com) old created pages looks ok, but newly created ones are showing this error:

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 ‘) AND t1.post_author = t3.ID ORDER BY rand() LIMIT 5’ at line 1]
SELECT t1.ID, t1.post_title, t1.post_date, t1.post_content, t3.display_name FROM wp_posts t1, wp_post2cat t2, wp_users t3 WHERE t1.ID=t2.post_id AND t1.post_status = ‘publish’ AND t1.ID != 95 AND t2.category_id IN () AND t1.post_author = t3.ID ORDER BY rand() LIMIT 5

You can see it here too: http://www.niggybuzz.com/useronline/

Any idea what is wrong and how I can fix that?
Thank you very much =)