this is just a guess, but i would suspect that the ad company is not screening the banner ads as closely as they should. it has happened in the past, where the bad guys have been able to slip in poisoned banner ads on major web portals and news sites. fortunately, it always gets corrected quickly. the advertising is necessary, since nothing on the web is free, but that is the one problem with advertising though... the ads come from sites that desktop nexus has no control over... so one has to trust that the ad company is effectively screening the ads that we get to see, and that they are safe.
it is just a guess, i would tend to think that DN, itself, is not the cause, but something external is going on... got to love the internet

toodles,
harmless