PHP - $_SESSION in IE6

Hi peoples. Im having some trouble with $_SESSION data magically dissappearing in IE6 (it works perfectly in IE7 and F-fox)

This is my php, from a file called “setup.php” which is the first file to be included in my template php page.


session_start();
if(    $_POST['username'] && $_POST['password'] ) {
    if($_POST['username'] == "correct" && $_POST['password'] == "correct"){
        $_SESSION[username] = "correct";
        $_SESSION[password] = "correct";
    }
}
if($_SESSION[username] == "correct" && $_SESSION[password] == "correct"){
    $loggedIn = 1;
}

Whats odd is that only in IE6, if i enter the correct username and pass, then hit submit on the login form, the page that loads reflects that you are now logged in…but then if i navigate to another page within the site (using the same template.php including the same setup.php) - the session data seems to dissappear…

anyone know why this is happening only in IE6?