the file you need should be here:
I can't imagine why it would not be there. After all, the hotpot script that wants to access it has apparently been safely installed. Perhaps it is there but is not readable? I'm not sure.
Anyway, if you could check whether "jquiz6.ht_" is where it should be, that would be a good first step.
I took the liberty of enrolling as a student in your Moodle site and was able to view the two hotpot quizzes in the "Vak101" course. They both seem to be showing up OK now, so it looks like the problem has fixed itself.
If the problem reappears, please let me know.
The Dutch language file capitalizes the descriptor string for the quiz's outputformat, "V6" in this case, and the module was using this string to create the path to the quiz templates directory.
I have changed the hotpot module, so that it will set the correct path to the templates directory no matter what language pack is being used.
There is one script affected, "moodle/mod/hotpot/lib.php". I have updated the new version to the CVS, so please download it from there when you have time. (in case you are in a real hurry, I have also attached it to this message)
Many thanks for your help in solving the riddle!