Sesson handling with cookie

Hi, PHP 4.2.2, MySQL 3.23.xx I have a problem destorying the actual session_id (SID)? I tried to use session_destroy(), session_unset, but nothing works, session_id() is always the same. What I want to do is: - After 30 Minutes if the user didn't do any work then let the session die - It must be work wheter browser's cookie is set or not? What Should I do to let it work? I successfully check if 30 minutes left after last (site)change, but I can't give a new Session_id(), after I let the user redirect onto the login page? Bye Alex Background: - I save the login information into database with the following columns: CREATE TABLE LOGIN ( MKMKOD varchar(20) NOT NULL default '', SESSION varchar(255) NOT NULL default '', LOGIN_TIME datetime NOT NULL default '0000-00-00 00:00:00', HOST varchar(15) NOT NULL default '', CURRENT_STATE varchar(255) default '' ) TYPE=MyISAM; - I check if it's over 30 minutes, on the current request: 'SELECT * FROM LOGIN WHERE MKMKOD = "'.$_mkmkod_.'" AND (DATE_SUB(NOW(),INTERVAL 30 MINUTE) <= LOGIN_TIME) AND HOST = "'.$_SERVER['REMOTE_ADDR'].'"'