Have a strange issue occurring with a site you're hosting, musiclandexpress.com

When I go to certain sections of the site, most notably Checkout, I get the Security Information dialog box telling me some items on the page are not secure. Strange this is, there is no difference on the page if I click Yes to view the unsecure items or No to not view the items.

This just started happening today. Anyone else experience something like this? Matt -- anything change in his setup that could be causing this?

Thanks!