What's wrong on line 10?
<?
session_start();
if ($username && $passwd)
{
// if the user has tried to login
$db = mysql_connect("LOCALHOST","NAME","PASS");
mysql_select_db("http_auth", $db);
$query = "SELECT * FROM http_auth WHERE name='$username' AND passwd=password('$passwd')";
$result = mysql_query($query, $db);
if (mysql_numrows($result) >0 )
{
// if they are indeed in the database register the username
$valid_user = '$username';
session_register("valid_user");
}
}