This is a fresh install, correct? In which case, the fact that you were logged in on first visit is abnormal. I can only assume then that you imported data from Chrome during Firefox setup? If this is the case, I would indeed advise that you follow TC's advice: ensure that all extensions are disabled, and clear cookies & cache (Tools -> Clear Recent History -> Everything). Given that the browser itself is also validated for login sessions here on Ø, cookies imported from another browser would certainly have the potential to cause the problems that you are encountering. Also ensure that cookies are actually being properly accepted: in the Privacy tab of the Options menu, select "Accept cookies from sites", and in the "Keep until" drop-down menu, select "they expire".