Arrrrgh! I spent ages formatting the phone and reinstalling today! Never mind, lol! Thats a bloody handy file to keep ahold of, for anyone who likes messing with the OS.
I also found
THIS, supplied by Nokia themselves. Apparently, it will restore the menu to the new format (it was meant for an up-dated phone that has been restored, mucking up with menus with original configuration).
Anyway, cheers hairilabubakar! It seems to me that if that file is the original, then deleting the menu.mif and over-writing the XML files should work after a reset.