http://blogs.msdn.com/tess/archive/2009/06/26/a-case-of-lost-session-variables-when-using-out-of-process-session-state.aspxRecently I had a case where the customer had an issue with session variables.  The claim was that if they use in-proc session state their session variables would work just fine, but if they changed the session mode to stateserver in web.config theirsv-SECommunityServer 2.1 SP1 (Build: 61025.2)