//So gehts:
require_once("D:\_config\page_mysql.php");
$link = mysqli_connect($forum_db_host, $forum_db_user, $forum_db_pass, $forum_db_name);

         //Mysql I -escape strings!
     $username = mysqli_real_escape_string($link,request_var('username', '', true));
     $password = mysqli_real_escape_string($link,request_var('password', '', true));
     $autologin = mysqli_real_escape_string($link,request_var('autologin', '', true));


//Orginal wie es vorher ging:
     $username = mysql_real_escape_string(request_var('username', '', true));
     $password = mysql_real_escape_string(request_var('password', '', true));
     $autologin = mysql_real_escape_string(request_var('autologin', '', true));