Sytax Problems. Need Help?

This is the error I got when I tried to add Back to Home Page Link in the Jump Menu. Can anyone help me the sytax.

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 'http://www.sharks-ent.com, 20' at line 1
Date : Sun, April 25, 2004 04:19:47

Browser : Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
Referer : http://www.sharks-ent.com/guestbook/index.php
PHP Version : 4.3.5
OS : Linux
Server : Apache/1.3.29 (Unix) mod_jk/1.2.0 PHP/4.3.5 mod_auth_passthrough/1.8 mod_log_bytes/1.2 mod_bwlimited/1.4 FrontPage/5.0.2.2634 mod_ssl/2.8.16 OpenSSL/0.9.6b
Server Name : www.sharks-ent.com