(Resolvido) sistema de login php e mysql

[magassomba]

alguém pode me dar uma ajuda nesses erros:

Warning: session_start() [function.session-start]: Cannot send session cookie - headers already sent by (output started at C:\Program Files\xampp\htdocs\dissertacoes\admin\connection.php:2) in C:\Program Files\xampp\htdocs\dissertacoes\admin\login.php on line 14

Warning: session_start() [function.session-start]: Cannot send session cache limiter - headers already sent (output started at C:\Program Files\xampp\htdocs\dissertacoes\admin\connection.php:2) in C:\Program Files\xampp\htdocs\dissertacoes\admin\login.php on line 14

Warning: Cannot modify header information - headers already sent by (output started at C:\Program Files\xampp\htdocs\dissertacoes\admin\connection.php:2) in C:\Program Files\xampp\htdocs\dissertacoes\admin\login.php on line 19

o código é esse:

<?php
include("connection.php");
include("function.php");
?>
<?php
$username=$_POST['user'];
$password=$_POST['password'];
if ($username && $password){
    $query="SELECT*FROM user WHERE username='$username' AND password='$password' ";
    $result=mysql_query($query,$connect);
    $numrows=mysql_num_rows($result);
    }
    if($numrows=!0){
                    session_start();
                    ob_start();
                    $_SESSION['autenticado']="SI";
                    $_SESSION['username']=$username;
                    $_SESSION['password']=$password;
                    header("location:cpainel.php");
                    ob_end_flush();
            }else{
    echo "<script language='javascript' type='text/javascript'>
            alert ('Os dados fornecidos são falsos!')
            </script>";
    header("location:index.html");
        }
?>

[ESerra]

Inverte isto:

session_start();

ob_start();

E coloca no topo do script...

[magassomba]

Obrigado! Essa valeu