where are you putting your session variables into a database, server-side or client-side with a cookie..
currently I have my php.ini settings server-side where it stores the session on my server within a temp session directory. when I ran you script as you post I get Jaaa without the errors, if remove the directory where my sessions are to be stored I mimic your error.. I don't know if that is your solution but it is a beginning..
I just looking up your session setting under php.ini I might be way off, seeing I perfer to use my own session management script..
But here are the settings I have turnon and was able to get your script to function:
[Session]
session.save_handler = files
session.save_path = /sessions
make sure that the path you have is available or you are not going to be able to generate a session..
session.use_cookies = 1
session.name = Session
session.auto_start = 0
session.cookie_lifetime = 0
session.cookie_path = /
session.cookie_domain =
session.serialize_handler = php
session.gc_probability = 1
session.gc_maxlifetime = 1440
session.referer_check =
session.entropy_length = 0
session.entropy_file =
;session.entropy_length = 16
;session.entropy_file = /dev/urandom
session.cache_limiter = nocache
session.cache_expire = 180
session.use_trans_sid = 1