Downloading non-secure content from a secure Web site

The Web site you are viewing is a secure site. It uses a security protocol such as SSL (Secure Sockets Layer) or PCT (Private Communications Technology) to secure the information you send and receive.
When sites use a security protocol, information that you provide, such as your name or credit-card number, is encrypted so that it can’t be read by other people. However, this Web page also contains items that do not use this secure protocol.
Given what you know about this Web site and your computer, you must decide whether to continue working with this site.

If you do not feel confident about working with this site, click No.

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The secure site is one we are working with, but I am accessing a page created with RoboHelp. I have asked the programmer why I get the warning that 'This page contains both secure and nonsecure items'. They are stumped. Does anyone know what would cause this or what would be on a page that would bring this message up. Something I can look for or eliminate from the page to get this message to stop.

TIA