I had this problem for months and finally figured out bwhat was causing it a couple of weeks ago. I was using http://www.flyertalk.com/forumcgi/Ultimate.cgi as my shortcut to FlyerTalk. So after I was going into a forum and then hitting the back button to get to the main "boards" screen, the cgi was getting re-executed. I guess sometimes it loses track of what it has done and thinks it is starting a new session, because it resets as you and I have experienced.

The way to defeat it is as follows:

1. Use the same link you are using to get to FlyerTalk now. (May not necessarily be the one I gave above.)

2. Go into one of the forums (any one is OK).

3. After you're done browsing the threads in the forum, don't hit the back button to get to the main screen. Instead, click on the link that says Flyer Talk 6.0. It's at the top of the screen, right in the middle. If you look at the URL in your browser, you'll notice it's quite different from the link you originally used to get to the FlyerTalk boards. It should have the string "bypassCookie" in it.

Works every time for me, hope it does the trick for you.