I think i found the solution.
Apperently it is known bug in windows. To get around it I had to
change this line
session_start();
to
if (isset($SessID)){ session_id($SessID); }
session_start();
header("Cache-control: private"); // IE 6 Fix.
setcookie("SessID", session_id(), time() + 3600);
That had fixed my problem.
Good luck to everybody and thank you for the advice