I just managed to lock up my Mac (which obviously isn’t possible), and had to remove the battery and power to hard reboot it. When I tried to restart NeoOffice (the mac equivalent of Open Office), it complained that my personal settings were already being used.
A quick look on the web identifies that there is a lock file that is left over by NeoOffic, but not where this was on MacOSX.
Its actually at /Users/<account name>/Library/Preferences/NeoOffice-2.1/.lock
Delete the .lock file, or mv it to .lockold and NeoOffice works again.