Session_start() issue??

Hi all, Has anyone seen this. I have a login form (login.htm) which calls a login handler (check_login.php). If the login is sucessfull the check_login.php will set a couple session variables, then redirect the user to a menu page. The problem I am seeing is that when I call session_start() from the menu page, I get a new session reference rather than a reference to the session I started in the check_login.php. Is there a setting in the php.ini I should change? Any thoughts would be greatly appreciated. Chris