Browser won’t display all images

I am using Internet Explorer 6.0.2800 SP1. The problem is that it won’t display certain images. For example, at the techrepublic.com site that I am at right now, the advertisements are missing and there is a symbol of a page with a red x in it. I know that not seeing the advertisements is not necessarily a bad thing, but it is more annoying and ugly than having them. I have security and privacy settings at default level, and I even tried disabling my pop-up blocker. Let me know what could be causing this and how to fix it. Thanks.