[Plugin: Yak] Do you wish to display secure & non-secure items?

I’m using Yak and when browsing via IE8 (or IE7, I assume), the checkout page is displaying “Do you wish to show both secure and non-secure items?” If the user clicks “no” to show only secure items, the information page goes crazy and gives them Canadian territory options instead of US states. I feel this may be causing another problem with confirmation emails so I need to start resolving these issues one at a time to see if they clear up.

In this case, what files would I need to make sure are secured under my domain to eliminate this message and knock it off my troubleshooting list?