Thunderbird opens as usual, but the pop-up asking me to sign in does not appear. I can access all the e-mails without signing in.. When I ask it to load in new messages, it establishes connection to the mail server and seems to upload the new messages. However, it just keeps 'loading' until the connection times out. It then shows me the time-out pop-up, but no new messages. - I have checked the mail server. It works perfectly fine and many new messages are there waiting to be uploaded by Thunderbird! - I have the newest updates! - I have successfully installed the new Thunderbird on top of the old one! ???