I think I spoke to soon in my earlier post. It turns out there was a problem with the reporting of HotPot results in Moodle 1.8. I think I have fixed it.
Please could you download the following file (right click on the link) and upload it to the "mod/hotpot" folder on your Moodle site.
http://bateson.kanazawa-gu.ac.jp/moodle/18/ms/mod/hotpot/hotpot-full.js
I hope this fixes your problem. Please let us know
regards
Gordon