It was my computer at work (only place I use IE). I tried it on IE on my home PC and it works fine. Work firewall must be blocking the website that the default avatars are coming from causing them to break.
Shame - those blasted carpet tile gravatars should be blocked - period. WHat the hell's the point of them? It's not as if they're memorable or give character to an user. All it means is that this guy couldn't be arsed to provide an avatar, so here's a shite carpet tile instead. Rant over.