Header('Cache-Control: no-cache, must-revalidate, max_age=0, post-check=0, pre-check=0');
header ("Pragma: no-cache");
header ("Expires: 0");

<?php
session_start();
header("Expires: Mon, 26 Jul 1997 05:00:00 GMT");
header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
header("Cache-Control: no-store, no-cache, must-revalidate");
header("Cache-Control: post-check=0, pre-check=0", false);
header("Pragma: no-cache");

include ("config.php");
include ($databasepath."/dbconfig.php");

if(isset($_COOKIE['cookname']) && isset($_COOKIE['cookpass']))
{
    $cpenname = $_COOKIE['cookname'];
    $cpassword = $_COOKIE['cookpass'];
    $cookie = "1"; // Pass and Username ok.
    /* Confirm that username and password are valid */
    $result = mysql_query("SELECT password FROM ".$tableprefix."fanfiction_authors WHERE penname='$cpenname'");
    if(!$result || (mysql_numrows($result) < 1))
    {
        $cookie = "0"; //Indicates username failure
    }
    $passwd = mysql_fetch_array($result);
    if($passwd[password] != $cpassword)
    {
        $cookie = "0"; //Password and Username confirmed
    }
}
/* User not logged in */
else
{
   $cookie = "0";
}

if ($cookie == "1" && $_SESSION['loggedin'] != "1")
{
        $_SESSION['penname'] = $_COOKIE['cookname'];
        $_SESSION['uid'] = $_COOKIE['cookuid'];
        if(isset($skinnew))
        {
                unset($_SESSION['userskin']);
                $_SESSION['userskin'] = "$skinnew";
        }
        $_SESSION['loggedin'] = "1";
        $_SESSION['adminloggedin'] = $_COOKIE['cookadminloggedin'];
        header('refresh: 0; url=/efiction/');
}

if ($_SESSION['loggedin'] == "1")
{
        $userpenname = $_SESSION['penname'];
        $useruid = $_SESSION['uid'];
        $skin = $_SESSION['userskin'];
        if(isset($skinnew))
        {
                unset($_SESSION['userskin']);
                $_SESSION['userskin'] = "$skinnew";
        }
}
.......