That's interesting. Firing off the cuff, it makes me think that it has something to do with cloud password storage. Most browsers offer this (it saves your passwords on any computer you are logged into)... The reason I'd guess that's the case is because if you go to the front page, it logs you in but fails to do it in other pages. What browser and version are you using? Also, I would try clearing your browsing history, cache, cookies, etc.