When using two massive nodes behind a load balancer with session affinity by IP, if you login and then go to the URL where the hostname is the hostname of one of the nodes, the login state is lost (it thinks you are logged out). So simulaneously the same user can be hitting the cluster via the load balanced hostname in one window of firefox, and in another window be not logged in in another window of firefox on the same box. This state can be maintained also (one firefox window can be adding anonymous comments, while the other window is editing pages in the same cluster as a logged-in user). To recreate this you may have to hit one of the nodes directly and click login (I forget if I did that or just went to the load balanced hostname).

This seems like a bug, but maybe it is just a byproduct of the way that firefox does things. Anyway- thought I'd let you know in case it helps.