I have been unable to reproduce this issue. It's not possible for the website to have a true "security error" as the website doesn't use https, the enhanced security version of http. That means none of the site is "Secure". Why not? Well, first of all, there's no sensitive information here that needs to be secured. You will never be asked for credit card info or any other personal data. It also costs money for a site certificate (like just about everything else on the internet) and having it would lead to more messages like that, not less, for example a "portions of this page are not secure" message if you link to an external image that's not on a secure website. Since that would simply cause confusion with very little benefit, we don't plant to install https in the short term.
From what I've been told, that issue is usually caused by either an ad blocker or a pop-up blocker. Both intercept and delete a portion of the data that the website is sending. If they pick the wrong part, you'll see errors. Since the alerts open a new window, they can be seen as ads or worse by some ad/pop-up blocking programs.
If your program allows it, "whitelist" this website, allowing ads and pop-ups. We don't run many ads and there are no pop-up ads at all, only things like private messages and alerts, which are content you presumably want to view.