Try some error checking on the mysql query:

eg:

[php]
$result = mysql_query("INSERT INTO shoutbox (id,ip,name,url,message,date) VALUES('','$ip','$name','$url','$message','$date')") or die('Error inserting into DB.');

if ($result) {

// ok
echo "Mysql Insert ok";

} else {
echo "DB Error, could not query the database\n";
echo 'MySQL Error: ' . mysql_error();
exit;
}

[/php]

the mysql_query() will return false if the query fails, and the last error for your mysql session/connection will be returned by mysql_error()