Second attempt at this post got logged out in the middle of first attempt. The one cookie I noticed vanish was session_lock. I've got the following bb cookies by the way bbcursession, bblastactivity, bblastvisit, bbpassword, bbsessionhash, bbthread_lastview and bbuserid. I've got screenshots of all the cookies both before and after if you want them. Unfortunately without values, but with domain, path, name, expiration, and site domain.