В ответ на: It could be some kind of ISP-based ad-zapper. such as this: http://www.lava.net/support/utilities/adzapper.html I've just looked at the source of a dgrin page, and because of the random way in which the pics are introduced, they may be seen as ads by the ad blocking s/w.
Follow up to the follow up: I've just spoken to one of the support people this end and he has confirmed that such server side software is in place. He will check if anything has changed recently.
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