Great,
it worked by using:
ini_set ('session.save_path', '/your/relative/path/for/your/sessions');
directly after:
define('QA_BASE_DIR', dirname(empty($_SERVER['SCRIPT_FILENAME']) ? __FILE__ : $_SERVER['SCRIPT_FILENAME']).'/');
in index.php .
Will test around now !
Thank You snoopy, very helpful hint !
monk333