In version, 1.6.6, the checkbox next to the terms and conditions label is not visible. When a registrant tries to continue, they receive the javascript verification notice; if they click the spot where the checkbox should appear they are able to contine. We turned the checkbox off until we can find a solution.
I guess that are some css conflicts causing the issue. Could you please submit a support ticket sending us admin and FTP account of your site so that I can ask my template developer to check and fix it for you on tomorrow morning ?