one thing you could try is downloading the most version of the HotPot module for your Moodle.
I think you are using Moodle 1.5, right? In that case, please download and install the most recent "stable" version of the module:
If you are using Moodle 1.6, please download and install the latest version of HotPot 2.1:
Please try one of the above and let us know how you get on.
all the best