Sessions ok with IE, broken with NS6 linux

Sessions are great when they work. Using PHP 4.2.2, Apache 1.3.26, and Linux OS, I have a "USER" stored solution for session variables using session_set_save_handler. (Mysql is session store if it matters, db is on another box.) Sessions work great with IE 5.5 browser, even between HTTP and HTTPS within same domain (my goal). Session id remains stable. Testing on client with Netscape 6.2 and Linux appears that the session id (PHPSESSID) is never "stored" by the client. Thus each refresh of my test page yields a new session_id. Again, the same debug web page displays a constant session id for IE5, but the session never sticks for Netscape/Linux. Both browsers are accepting cookies, so the PHPSESSID isn't appearing in the URL. HELP! Thanks, me.