(Seemingly) random session destruction

[eluser]WanWizard[/eluser]
I don't see anything wrong with this code (disclaimer: I'm still on my first coffee).

Guess it's time for some serious debugging. Start by activating the profiler so you can look at the contents of the session after each page request, and the queries that are run against the session table. That will show you what happens with the session_id.

If it changes after you're thrown back to the login, you will have to add some debugging to the session library to see the contents of the cookie received, and the actions the libraries takes. Use firebug or log_message() calls. If it doesn't change, than the issues is not in the session library, but elsewhere. Again, the contents of the session in the profiler should show you what is missing, and might lead you to the code that deletes those missing items from the session.