OK, the runtime error 5 is gone now.
I open DefaultLg.dat and another file (empty). I click on a string. Nothing but "?????????????". I click another string and it says first "You have changed something, would you like to save it now?" and I've changed nothing! Then it goes to the other string, again "???????????????" or sometimes "??????4?????" or "??????????5?". Has this something to do with the Unicode?