Steps to reproduce (with luck): - Start Thunderbird - Close Thunderbird - Start Thunderbird When starting now I get this "Close Thunderbird" message: "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." The only thing that helps is "killall thunderbird-bin".
*** This bug has been marked as a duplicate of bug 296721 ***