Formular smadrer session

Hej

Når jeg kører formularen i dette script bliver jeg sendt til login.php:

<?
session_start();
include("connect.php");
$id = $_GET[id];


if(!isset($_SESSION['id'])){
    print("    <script language='javascript'>
        location.href='login.php';
        </script>");
       
}else{
$query = "SELECT * FROM users WHERE id = '".$_SESSION['id']."'";

$result = mysql_query($query)or die("MySQL fejl: " . mysql_error());
$log = mysql_fetch_array($result);
$user = $log["user"];
echo"$user";
$query2 = "SELECT * FROM messages WHERE modtager = '$user' && laest = 'n'";
$result2 = mysql_query($query2)or die("MySQL fejl: " . mysql_error());
$log2 = mysql_fetch_array($result2);
if(isset($_POST[text])){

$query3 = "SELECT * FROM topics WHERE id_parent = '$id'";
$result3 = mysql_query($query3)or die("MySQL fejl: " . mysql_error());
$log3 = mysql_fetch_array($result3);

          $sql = "INSERT INTO topics (titel,text,date,author,id_parent)
            VALUES ('%s', '%s', '%s', '%s', '%s', '%s', '%s', '%s')";
        $sql = sprintf($sql,
            mysql_real_escape_string($log3['titel']),
            mysql_real_escape_string($_POST['text']),
            mysql_real_escape_string(now()),
            mysql_real_escape_string($user),
            mysql_real_escape_string($log3['id_parent'])
            );

        $res = mysql_query($sql) or die(mysql_error());
       
}


$foresp = mysql_query("SELECT * FROM topics where id_parent = '$id'") or die(mysql_error());

while ($row = mysql_fetch_array($foresp)) {
  echo"<br><br>Titel: $row[titel]<br>Text: $row[text]<br>";
 
  echo"<form method='post' action='$PHP_SELF'>
  <textarea name='text'>Skriv en meddelelse</textarea>
<input type='submit'></form>";
}
}
?>