Internet explorer problem sessions

[eluser]OnurTEZ[/eluser]
Thank you in advance;

İnternet explorer session not open, No problem with other browsers

Controller my file:

Code:

function giris_kontrol()
    {
        //post ıle gelenler degıskenlere atandı
        $email = $this->input->post('email');
        //$sifre =  md5(sha1($this->input->post('sifre'));
        $sifre2 =  $this->input->post('sifre');
        $sifre = sha1(strtolower($email) . ($sifre2));
        $kullanici = $this->uyelik_model->kullanici_bul($email,
$sifre);
       if( !$kullanici )
                {
                        $this->session->set_flashdata('uyari', 'Giriş başarısız';
                        redirect(site_url('uyelik/giris_ekrani');
                }
                else
                {
                        if( !class_exists('CI_Session' ) $this->load->library('session';
                           $durum = $kullanici->yasak;
                        if($durum == "1"
                         {
                        $session_bilgileri = array(
                                'email' => $kullanici->email,
                                'ad_soyad' => $kullanici->ad_soyad,
                                'seviye' => $kullanici->seviye,
                                'uye' => TRUE
                        );
                        $this->session-
>set_userdata($session_bilgileri);
                        redirect(site_url('uyelik/bana_ozel');
                        }
                        elseif($durum == "0"
                         {
                        $this->session->set_flashdata('uyari', 'Hesabınız Engellenmiş!';
                        redirect(site_url('uyelik/giris_ekrani');
                        }
                }
        $this->session->set_flashdata('hata', 'Bilgileriniz Eksik Yada
Yalnış!';
        redirect(site_url('uyelik/giris_ekrani');
    }