Sessions do not persist

I resolved the issue after I noticed that:
- when the URI contained the character "1" the sessions seemed to carry over
- preventing the http-referer from being sent also seemed to have an effect on whether the session would be kept

Found this setting in php.ini:

session.referer_check = 1

Seems harmless at first, except: "session.referer_check contains the substring you want to check each HTTP Referer for. If the Referer was sent by the client and the substring was not found, the embedded session id will be marked as invalid. Defaults to the empty string."