When you visit a secure page (using HTTPS protocol), "This page contains secure and unsecure elements" displays because the browser has detected that not all elements on the page are secure.
When a page is called via a secure SSL call, the browser checks to make sure that all the elements on it can be loaded safely. IE the location of the elements being the web page, images, etc all fall under the secured URL, If there are any links to images, media or scripts that do not reside under the the URL IE HTTPS://... then you will get this error.
To prevent the message from displaying, please re-write all your pages links with HTTPS calls, and do not load any external pages with HTTP:// use HTTPS://
