Problems with Gmail and Thunderbird
If your Gmail is full and you think you need to store all your old e-mails to your computer, you may consider using Thunderbird. But you might encounter some problems when using it. Here I collected some links regarding the problems and solutions.
Gmail: Move all emails in trash to inbox
How to Uninstall Thunderbird Completely and Then Reinstall It
“Thunderbird is already running, but is not responding. To open a new window, you must first close the existing Thunderbird process, or restart your system.”