IE has been famous for the Red x situation going back to version 6. See below site for showing pictures in IE8
http://support.microsoft.com/kb/283807
The reason being the red x's are because you have to clear your temporary internet files on your computer. To do so go into the internet settings in IE and click DELETE TEMPORARY and INTERNET FILES, after doing so the websites that you visit will no longer have the red x's . If they still show up this is because of a problem with the web pages HTML coding. Red x's indicate that the file that the images for that site has been moved. If there are no images for the page, then the images cannot be seen. Therefore the computer has to show something so it shows you a red x. Also another thing that my be happening is that you have your content set to block these sorts of pictures. If you set your computer to block xxx pictures for example, then if you went to a xxx site then all the pictures wouldn't show. They would appear as red x's or as gray squares on your screen.
To clear temporary Internet files, follow these steps:
Internet Explorer 8
1. Start Internet Explorer 8.
2. On the Tools menu, click Internet Options.
3. On the General tab, click Delete under Browsing History.
4. In the Delete Browsing History dialog box, click to clear all of the check boxes except for the Temporary Internet Files check box, and then click Delete.
5. Click OK to close the Internet Options dialog box.
Verify that the Show Pictures option has not been turned off
If the Show Pictures option in Internet Explorer is turned off, you cannot see pictures. To determine whether the Show Pictures option is turned off, follow these steps:
1. On the Tools menu, click Internet Options.
2. Click the Advanced tab, and then verify that the Show Pictures check box is selected under Multimedia.
3. Click OK.
Here is another reason it may show the red X: ......................
I've found the problem with IE8 showing X's where some pictures were supposed to be and certain videos not playing.
Yesterday I found that on my wife's laptop, IE8 was working flawlessly. I knew then the problem had to be with "me" ...
I installed IE8 back over IE7 again, and the same red x's showed up and CNN video's not playing. THEN, I noticed up in the address bar, there it was ... an option showing itself quite clearly, asking me if I wanted to allow Adobe Reader to work on this site alone or all sites. Clicking that, and allowing Adobe to work on all sites fixed the problem.
"We the People are the rightful masters of both Congress and the Courts--not to overthrow the Constitution, but to overthrow the men who pervert the Constitution." Abraham Lincoln