From QED

Microsoft Internet Explorer

To disable the popup warning "This page contains both secure and nonsecure items", follow these steps:

1. Select "Tools" in the MSIE menu bar.
2. Select "Internet Options..." from the drop down menu.
3. Click on the "Security" tab.
4. Click on "Internet".
5. Click "Custom level...".
6. Scroll down to find the heading "Miscellaneous".
7. Find the sub-heading "Display Mixed Content".
8. Click Enable.
9. Click OK.
10. In response to ‘Are you sure you want to change the security settings for this zone?’ click Yes.
11. Click OK to close the Internet Options box.