We have a cluster behind a Coyote Point E350si load balancer that is running VBulletin, and what's happening is that with HTTP_X_FORWARDED_FOR header insertion turned on, while logged in to the site a pages will randomly load as if you weren't logged in. After about 20 seconds of idle time it's almost assured that the next click will load a page like you weren't logged in, but hitting refresh will load it just fine. All of the persistence options are turned on in the load balancer.

Any ideas would be very helpful! We have contacted the VBulletin guys and they are fresh out of ideas, and we're waiting to hear from the Coyote Point peoples to make sure we didn't missconfigure the balancer.

We are running Debian Stable, with stock packages aside from a few things in PECL, and for memcached.