I recently worked on a website where images were displaying in Firefox but not IE (Internet Explorer).
I did a variety of testing. I thought it might be due to the way it was referenced or the format.
It turned out it was because the image was a CMYK jpg image. IE requires it to be RGB for it to display.
To make the image display correctly in IE. Simply paste the image into Photoshop or Paint, and change the settings to RGB.
The problem definitely had me scratching my head. Another reason to forget about IE