I get the "Your session has expired, please log in again" occasionally first thing in the morning. I play on 2 worlds F/en6 and H/en8, so first thing I log into both worlds in separate browsers, to collect my overnights more speedily. The error occurs when I inadvertently log into the same world on both browsers and then log out again on one browser (in order to log into the other world). I then get the "Your session has expired..." on the browser which remains logged in, because I just logged out from the other browser.