Technote Details :: Session variables are not passed between pages on Windows
Issue
When working with session variables on Windows based servers, the variables might not get passed between pages, and multiple sessions are created.
Reason
When transmitting session variables from one page to another you have to transmit the session ID first. There are three ways to do this:
1. session ID is transmitted automatically by the server when session.use_trans_sid = 1 (set in php.ini)
2. session ID is store in a cookie when session.use_cookies = 1 (set in php.ini)
3. session ID is transmitted manually by the user in the URL
Under Windows environment session.use_trans_sid = 1 doesn't work. Therefore when calling session_start in another page the session ID is unknown and another session is created.
Solution
To be able to use session variables in sites on a windows environments, you have to set session_set_cookies = 1 in php.ini.