Switched language and can't switch back

I am running MuseScore 0.9.6.2 on Mac OS X 10.6.4, and have encountered a problem whereby I seem to have modified the language but now cannot change it back.

I think when I was trying to set up the MIDI settings (which now work, by the way) I inadvertently changed the language from English to something else, and although I thought I had changed it back, when I restarted MuseScore many of the drop down menus and items in the palette (though not all of them) had become either Chinese or Japanese characters. Also, when I visit the online help manual it defaults to a different version, so the software must think I am working in another language, though interestingly some items are still displayed in English (such as "Key Signatures", "Time Signatures", "Note Heads"...)

More concerning is that I now cannot reopen the preferences, either from the MuseScore menu or by the keyboard shortcut Apple-,

I have tried reinstalling the software, but nothing has changed. I tried deleting what I thought were the appropriate preference files but also, no success.

Could someone recommend either how to fix this, or what I need to do to wipe the software completely from the system so I can do a clean install that will hopefully solve the issue.

All other aspects of the software still appear to work.

Many thanks in advance.