IE 8 warning – 'Do you want to view only the webpage content that was delivered securely?'

Introduction 

This problem happens when we receive a security warning in Internet Explorer 8 when we visit a web page that is hosted on a secure website. In IE7 and below a different message is displayed.

Background 

In a project, Microsoft Reporting Service is used and to print, a separate print button is given (not sure why), which opens the htm page and does window.print. The site is hosted on HTTPS. In IE every time we get a warning message "Do you want to view only the webpage content that was delivered securely?"

Debug the Code 

After googling many things and setting up many proxy tool, unable to conclude anything.  Got almost same answer like it may use http in https somewhere and that is the causing the problem. Then I tried with debugging the java script code for that htm page using IE developer tool. Somehow I was able to conclude that due to following line it was causing the problem. 

tRow.removeChild(tRow.firstChild);  

Again started searching for this, can this be really a problem in https? Got following KB link: http://support.microsoft.com/kb/925014.

It did not match exactly with my problem, however I changed code with following line,  

tRow.firstChild.innerHTML = "";

Interestingly it worked and the popup was gone.

Points of Interest

Strange with this behavior of IE because in most of searches it was said it is due to accessing HTTP content from HTTPS. Never thought this could be the problem.

Happy coding.