Is the folder pane and the message list pane are blank? Then the pane system did not initialize. We find so far that users have a folder that causing the problem, and the name of the folder will likely be shown in the error console. Check tools > developer > error console for errors (not warnings) about folders or panes. Please post what you find. If only unified folders is the problem then # open the troubleshooting information on the help menu. # Click the show profile button # Close Thunderbird # Open the "mail" folder in the file manager window that opened. # Delete the folder named "smart mailboxes" # Restart Thunderbird.