It was time to update the computer I'm using, and I ran all of the updates except for the upgrade from IE6 to IE8. I'm using a work computer, so I'm simply not allowed to upgrade from IE6 to anything useful (some of their stuff apparently still requires IE6). I use Chrome on the side, but I need IE for certain things.
After updating and restarting, I found that pictures in general stopped showing in IE6, except for occasional ads. Even the Google logo does not show up. In Chrome, however, everything works fine. I already tried going to Tools->Internet Options->Advanced->Multimedia and checking "Show Pictures" (which was already checked), and nothing on the "why your pictures won't show!" pages online seem to help.
update: When I'm on the Google homepage, the bar at the bottom of the IE window says "Downloading picture http://...", and I suspect it's not the only page that says that, but there's a red X in the place of the logo, which I thought meant the browser had already given up.
update (some time later):
I was able to upgrade to IE7 and I'm having the same issue. In both cases, there are certain images that show up, and certain ones that don't. I'm wondering if images got set to
display: none !important somewhere. Looking into it.
update (even later; haven't had much time to deal with this): Just discovered that all the missing images are apparently .png files.