Found it. It's Nessa's avatar.
Firefox doesn't have a problem with it, but does block the actual site (
http://avatarswizard.com)
I'll nick the image for her and load it onto our server. That should stop Chrome throwing tantrums. The gif itself should be fine, but I'l check it first of course.
Devious, treacherous, murderous, neanderthal, sub-human of the West.