1. Navigate to the page using Internet Explorer. You will receive the typical security warning, and you will be prompted whether or not you would like to display the non-secure items on the page. If you select not to display the items, the page will load without them. If the unsecure items are images, they should be easy to detect, as you will see a broken image link on the page for each image that is not called through the secure URL. If you do not see any broken or missing images on the page, it is likely a javascript or css include that is causing the problem.
2. While viewing the page, click View-->Source to view the HTML source of the page.
Click CTRL-F or click on Edit-->Find on this page to open a search box.
Enter 'src=' and search the page for every image and script item, making sure it is called through 'https://' (NOTE: if you are calling an cross-domain script or image, such as a Google Analytics include, you will need to make sure that the script or image can be called through a secure URL before changing your code or it will still generate a security error).
Next, in the <head></head> region, search for any '<link' tags and make sure that the 'href=' attribute is called through the secure URL.