Browsers Don't show clickable gif images

My main rig doesnt show the images that are clickable when I am surfing. It doesnt matter if I am using opera or IE. It's not terrible but it is kinda annoying to see those little x's with boxes around them where a image should be. any ideas how to rectify this?

Here is a shot of my Yahoo mail. It doesnt show any of the ad images. Its nice for some sites but on others I would like to be able to see the clickable images.