The forum uses two seperate cookies, a "remember" cookie (only set when you click "Remember Me") and a session cookie - the session cookie lasts as long as your browser stays open, but is invalid if you haven't done anything on the forum for the past hour.
There was a bug that occured when your session cookie has expired, but the browser has not been closed. I've fixed that, and I've also fixed cookies so that they work for the .gossamer-threads.com domain - meaning that they'll work for links to www.gossamer-threads.com/... and gossamer-threads.com/...
Jason Rhinelander
Gossamer Threads jason@gossamer-threads.com