I've logged into chat.stackexchange.com several before and been able to chat, so I'm sure my account is signed up there, however I can't login there now. Whenever I go to:
https://chat.stackexchange.com/login/global?returnurl=http%3a%2f%2fchat.stackexchange.com%2f
... I always get the error 'Your login data seems too old; please log in to any StackExchange site to refresh it.' I've tried logging out and logging in again in other StackExchange sites, closing/opening the browser (Firefox 3), and even using another browser with a fresh profile (Opera 11), but I continue to get the same problem logging into chat.
UPDATE: Looks like the problem only happens with the subdomain chat.stackexchange.com. So, I visit:
https://chat.stackexchange.com/rooms/95
... for example, and although I can see the chat, it seems to think I'm not logged in and says I must log in to be able to chat. I can't login because of the above problem. However, I can chat no problem on, say: