found solution:
http://mu.ww.wp.xz.cn/forums/topic/11580
in wp-config add:
define(‘ADMIN_COOKIE_PATH’, ‘/’);
define(‘COOKIE_DOMAIN’, ”);
define(‘COOKIEPATH’, ”);
define(‘SITECOOKIEPATH’, ”);
(I know it’s old post but i found it in the beginning and it took me next 3 hours to find solutions.. so maybe someone will have this 3 hours extra 😉 )
