Problem with NA and JP version installed

[bigbig1982]

Well I always played on JP version, now I wanted to try NA too, so I got the game and installed it on another HDD but a problem pop up...now if I try to play JP version it doesnt work. Once I login on JP, go to FFXI page, click Play and go full screen, it shut down, not only FFXI but the whole POL. I dont know if its the same on NA version cause I still have to do the update of the game there. Sounds like a conflict between files, but how can be if they are installed on different HDD??? Do you have any idea?