Thought about making a smartass remark about it's because you're on a Mac...But I won't x]
It's most likely a Javascript problem. Make sure you're all up to date.
Adobe and Java. Or try right-clicking and choosing "Reload Image/Show Image" or the equivalent on Mac >.<

since middy posted that, i'm gonna assume it's hosted on zerrit.

if the image link is avatar.pure34, then that is why.

it was an imagehost provided by one of the users of jsp, but his hosting ran out and took the images with it.