Sessions work correctly if session.save_handler is set to 
'files', but if I set it to 'user' and I set up a new save 
handler with session_set_save_handler(), then afterwards I 
have to call session_write_close() at the end of every 
script, otherwise the session data doesn't get written out 
(to a database in my case)

I tested it with PHP 4.0.6, and apache 1.3.20.
PHP has to following extensions loaded: gd, mysql, ldap.