I had Firefox 4 beta installed along side firefox 3.6 before firefox 4 was released. After firefox 4 was released, I uninstalled the beta (ensuring not to delete my prefrences when uninstalling). Then I started up firefox 3.6 and I noticed that all my settings had vanished (but the addons were still there) and I was logged out of firefox sync. So with the confidence in mind that I had all my settings backed up to the firefox sync server, I attempted loging into firefox sync. It accepted my User Name and Password entries but for some strange reason, it refused to accept my key entry; which was in the older versions called the secret phrase entry (so I still had my secret phrase as the key). Attempted loggin into the latest version of FirefoxSync home on my iPhone and it worked as expected, plus it showed the correct number of bookmarks and history infos. Why isn't firefox sync accepting my sync key, aka secret phrase? I 99% doubt this but could it be getting blocked by some entries in my "host" file as I recall adding tonnes of adblocking entries to it; preventing my computer from wasting bandwidth loading them. BTW I attempted loggin into this firefox sync site and it kept showing me that it couldn't log me in :( Or is the site not meant for viewing what's stored on the server? https://account.services.mozilla.com/