Thunderbird won't start

Thunderbird closed unexpectantly (maybe due to a powercut) and now won't open. It gives an error along the lines of "Thunderbird is already running, but not responding. To open a new window you must first close the existing Thunderbird process, or restart your system".

These commands work under the DAMTP MacOSX and Linux systems.

Open a terminal or xterm window and run the commands

	killall thunderbird-bin
        unlock-thunderbird