Tokina.
The watermark is hard-embed on the image at the time of their upload. Our image hosting solution has nothing to do with vbulletin's crappy one (and we don't use it)
In our last diagnostic, the issues actually result from partially load images. For some reason, your connection, your browser, or the ISP connection, or our CDN servers never transmit the image fully. In fact, what it get is only a first few KB of the image and it reported as fully loaded, or the connection was cut-off unexpectedly.
The problem seems to happen to a very few people, and we cannot reproduce it at anywhere of our ends.
Can you restart your modem (get another IP) and try again? Also try to download the said image using a download manager, such as Internet Download Manager or alike, try to see if you can fully download the image down.