Hi,
1. It's a HikaShop popup related problem.
Please change the "popup mode" to "mootools" in your HikaShop configuration (section "display").
2. You can override the view "checkoutmarket | terms" in order to not display the first checkbox.
The best will be to replace the content by
<input class="hikashop_checkout_terms_checkbox" id="hikashop_checkout_terms_checkbox" type="hidden" name="hikashop_checkout_terms" value="1" />
So the rest of the algorithm will still see the store checkbox as "checked".
Otherwise you might not be able to continue in the checkout and confirm the order.
Regards,