Reason:    This is because the presentation uses the msorun.cab file that is downloaded from a unsecured Microsoft site when the presentation is loaded thus alerting the user that a component of the web page is coming from an unsecured site.

Fix:

1. Download the cab file here.
2. Edit the frame.htm file and chnage the path of the cabfile. Note: For some crazy reason the folder that contains the files for your html published PowerPoint presentation is hidden when you are running it from a SharePoint site. Thus you must open the original .ppt file and 'Save As' the PowerPoint presentation in .htm to your DESKTOP and then edit the "frame.htm" file in the folder that it creates. In the frame.htm search for:
   1. http://download.microsoft.com/download/PowerPoint2002/Install/10.0.2609/WIN98MeXP/EN-US/msorun.cab#version=11,0,0,1
      
   2. and change it to: msorun.cab#version=11,0,0,1 (this will make the path to the cab file the same as all the other files (secured) and relative to the frame.htm document)
3. Place the cab file in the PowerPoint folder that is on your desktop.
4. Upload the whole thing (xxxx.htm, and the PowerPoint folder) to your sharepoint site.