The thing is that if you disable quickview from theme configurator module then the following script "/js/jquery/plugins/fancybox/jquery.fancybox.js" is not called anymore, and you need fancybox() function in registration for terms & condition popup
So the issue is the popup of Terms & Conditions window, right?
This seems happens at old version of PrestaShop, it does not happens in latest version of PrestaShop 1.6.1.4.
But we have also fixed this issue. You can contact [email protected] to request a patch to fix the issues.