That's an error that appears if you don't change your number format to Japanese. The Readme file packaged with the game will tell you how to do so (Don't worry, it's easy!)
Oh, that's really embarassing, I'm sorry.
I did read the readme file, but I thought it was reffering to, that the computer system needs to be in Japanese, and since mine is I didn't bother to follow the steps.
So, my bad...
Again, sorry for asking this question.
(Man, it is explicitly mentioned, and still I ask :blush:)