Problemi login e cookies

[Gorgoglius]

Ciao a tutti.. ho un problema con i cookies riguardanti il controllo di login di un utente.. ho due pagine admin.php (dove c'è la form) e auth.php (dove ci sono le funzioni)

admin.php

<?
        include_once("auth.php");
        include_once("header.php");
        include_once("menu.php");
        
if(!isset($_POST["user"])) {

echo '
    
    <div class="content">
        <div class="left">
            <div class="item">


    <form name="form" method="post" action="admin.php">
        

Ola, se fai parte dello staff del sito inserisci il tuo Nick e la tua Password per accedere all’area riservata!!</p>
        

Nick:

          <input type="text" name="user">
          

          Password:

          <input type="password" name="pass">
        </p>
        

 
          <input name="Login" type="submit" id="Login" value="Login">
          <input name="Cancella" type="reset" id="Cancella" value="Cancella">
        </p>
    </form>
    

            </div>    
        </div>
        <br class="clearer"/><span></span>
    </div>

';

}else{

    if(login($_POST["user"], $_POST["pass"]) == 0) 
    
      {
        
        $connect = mysql_connect(HOST_DB, USER_DB, PASS_DB)
            or die("Connessione non riuscita");
        
        mysql_select_db(NAME_DB) 
            or die("Selezione del database non riuscita");
        
        $query = "
            
                SELECT *
                FROM `utenti`
                WHERE `nick` = '".$_POST["user"]."'
                AND `password` = '".$_POST["pass"]."'
             
                 ";
        
        $sql = mysql_query($query)
            or die("Query fallita: ". $query);

      echo '
        <div class="content">
            <div class="left">
                <div class="item"> ';
                        
                        while ( $dati = mysql_fetch_array($sql) ) {
                        
                          echo '<h1> Ciao '.$dati["nome"].' '.$dati["cognome"].'!!</h1>';
                        
                               }; 
      echo '
                                    
                </div>    
            </div>
            <br class="clearer"/><span></span>
        </div>
      ';

      } 
    else{
    
      echo '
        <div class="content">
            <div class="left">
                <div class="item">
                <h1>Opssss</h1>
                

Ue furbacchione.. le possibilità sono due: o hai sbagliato a fare il login, oppure mi sa tanto che non hai l\'autorizzazione ad entrare in questa sezione protetta.</p>
                </div>    
            </div>
            <br class="clearer"/><span></span>
        </div>
      ';
      }
      
}
        include_once("footer.php");


?>

auth.php

<?php

include_once("config.php");

function auth(){

    if(isset($_COOKIE["USER"])) {

        $connect = mysql_connect(HOST_DB, USER_DB, PASS_DB)
               or die("Connessione non riuscita");
        mysql_select_db(NAME_DB) 
            or die("Selezione del database non riuscita");
        
        $query = "
        
        SELECT * FROM `sessions` WHERE
        `user` = '". $_COOKIE["USER"] ."' AND `pass` = '". $_COOKIE["PASS"] ."' 
        AND `session` = '". $_COOKIE["SESSION"] ."'
        
        ";
           $result = mysql_query($query) 
            or die("Query fallita");

        $line = mysql_fetch_array($result, MYSQL_ASSOC);

        if(mysql_num_rows($result) == 1) {

            $auth = 0;
            
        }else{
    
            $auth = -1;

        }
    
        $query = "DELETE FROM sessions WHERE time < ". (time()-(60*60*24))  .";";
        mysql_query($query);

    
        mysql_free_result($result);
        mysql_close($connect);
    
    
    }else{

        $auth = -1;
        
    }
    
    return $auth;
    
}


function login($user, $pass) {


    $user=$_POST['user'];
    $pass=$_POST['pass'];
    
    $pass=urlencode($pass);

    $connect = mysql_connect(HOST_DB, USER_DB, PASS_DB)
        or die("Connessione non riuscita");
    
    mysql_select_db(NAME_DB) 
        or die("Selezione del database non riuscita");
        
    $query = "
            
            SELECT *
            FROM `utenti`
            WHERE `nick` = '".$user."'
            AND `password` = '".$pass."'
             
             ";
    
    $sql = mysql_query($query)
        or die("Query fallita: ". $query);

    $numrows=mysql_num_rows($sql);
        
    if ($numrows == 1) 
    {
      
          $time = time();
          $session = time()+$user+$pass;
                
          mysql_query("INSERT INTO session (user, pass, session, time)
          VALUES ('" . $user . "', '" . $pass . "', '" . md5($session) . "', '" . $time . "');")
            or die("Query fallita");
    
          setcookie ("USER", $user);
          setcookie ("PASS", $pass);
          setcookie ("SESSION", md5($session));
          setcookie ("TIME", $time);
    
          return 0;  
    }
    else
    {
          return -1;  
    }

    mysql_free_result($result);
    mysql_close($connect);
    
}

?>

Nel file config.php ci sono le variabili di connessione al db.
Mi da questi errori:

Warning: Cannot modify header information - headers already sent by (output started at c:\programmi\easyphp1-8\www\cpg\auth.php:111) in c:\programmi\easyphp1-8\www\cpg\auth.php on line 93

Warning: Cannot modify header information - headers already sent by (output started at c:\programmi\easyphp1-8\www\cpg\auth.php:111) in c:\programmi\easyphp1-8\www\cpg\auth.php on line 94

Warning: Cannot modify header information - headers already sent by (output started at c:\programmi\easyphp1-8\www\cpg\auth.php:111) in c:\programmi\easyphp1-8\www\cpg\auth.php on line 95

Warning: Cannot modify header information - headers already sent by (output started at c:\programmi\easyphp1-8\www\cpg\auth.php:111) in c:\programmi\easyphp1-8\www\cpg\auth.php on line 96

Quelle righe sono le righe (appunto ) dove ci sono i 4 setcookies:
setcookie ("USER", $user);
setcookie ("PASS", $pass);
setcookie ("SESSION", md5($session));
setcookie ("TIME", $time);

Come risolvo?? Grazie