Ooookaaay. There is something really weird happening. I login, it shows that I am being redirected on the front page, then I am still logged out - unless I click on a thread, where I show as logged in...
Back to normal for me too.
Only one cookie at the moment. that might have been a red herring but thought wroth mentioning. some sites leave one cookie, some two, some more. I'd always noticed TPL laves two, one just name for the domain one with the www
I'm trying again with the caching that I tried yesterday. It will be worth it if I can get it to work. Can you try changing pages a few times without re-logging in and let me know if the login issue persists?