After working normally for more than a year, last week when I started Thunderbird there was a popup page with an error message that kept repeating itself "Sorry, we're unable to communicate with our sign-up server. Please check your connection." And behind this error page was the main Thunderbird frame with tool bars, but nothing else. All the email and email folders had disappeared. I have the same Thunderbird setup on my upstairs desktop computer, just like this one, and it's working perfectly. And no connection problems anywhere, I also have other email programs that are working normally. What does this problem look like? And is there a way I can check the profile to make sure the email and email folders are still intact. Is there a way to know if the profile is corrupted, and does Thunderbird keep duplicates of the profiles? I'd appreciate any troubleshooting help... John