In SharePoint 2003 or 2007: If you’ve ever seen the “This page contains both secure and nonsecure items” error message, this post is for you. It pops up when you add an RSS reader web part to a page on a site that was in my Trusted Sites or Intranet Sites zone. This has annoyed me for a while, and after a little playing around in IE 7’s settings, I figured out how to get rid of it.
From IE 7 (pretty sure this is the same with IE 6) access the Tools menu, then Internet Options. Click on the Security tab, then select the zone your SharePoint site is in (for example the Internet Zone), the click the Custom Level button. Then scroll down to the Miscellaneous header and look for “Display mixed content” and set it to Enable. Click OK and exit IE, then open it up again and see if the message goes away. Verify the zone that IE has this site listed in by looking at the bottom toolbar of the IE window.
