I've done both of those now.
Clearing the cache didn't help.
And as for what that area of the source looks like, it's the same as another user's post except that the img src is shorter. It's simply
Code:
image.php?u=30&dateline=2007
whereas other user's datelines are at least twice as long.
Oh, and I tested this on IE (I normally use Firefox here at work) and with IE, the avatar simply shows up as a broken image link complete with red X.