Error w/ 2.4.3 Update

Help! I updated my AGB, followed step by step instructions and everything woks great...except when I try to "sign the guestbook" I get this error:

MySQL Error : Query Error
Error Number: 1064 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 'SET session_id='55f281d114b548daebcfb09cf49069a9', validate_key=
Date : Wed, September 12, 2007 22:13:20
IP : 12.1.219.253
Browser : Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1)
Referer : http://www.phhs1985.com/Guestbook/
PHP Version : 4.3.11
OS : FreeBSD
Server : Apache/1.3.33 (Unix) FrontPage/5.0.2.2510 mod_fastcgi/2.4.2
Server Name : www.phhs1985.com