Why won't this GIF show in IE?

I’m at a loss here. The image on the right shows fine on my Mac, and it shows fine in FireFox on my Windows XP PC, but on IE6, it shows as a broken image.

Here’s what identify has to say about it:

UI11-badge.gif GIF 90x57 90x56+0+0 PseudoClass 256c 2kb 0.000u 0:01

Does anything look wrong here? What to do, where to look?