This message shows up on secure pages and sometimes it’s really hard to find what’s causing it.

Since your page is secure, all the external files, including CSS files, Javascript include files and images need to be linked from secure https pages in order for IE7 to load your page without errors. The Fiddler tool helps identify which images/files are not being linked from https.

Once you install it, just run it and open the page you want to test in a browser. Here’s my screenshot that found that offending image in no time: