[eluser]WanWizard[/eluser]
Haven't looked into it any further, other then that my assumption about cookie deletion due to the length was not correct.
IE and FF happily accept very long header lines, Chrome aborts with a 503 error when that happens. None of them cause the session to be reset.
I don't build CI applications anymore, so no real incentive to spend more time looking into it at the moment.