Gravatar does not display in Firefox

Okay Firefox and Opera are failing to display my Gravatars, whether they’re on an author page or a single page or in comments. Flock, Safari and Netscape show it just fine. I’m guessing there’s something quirky here that the gecko kit is tripping on like the fact that image is padded with a border or something?

If anyone knows the bug behinds this, much appreciated.