Hmm we've got the couple of banner ads that appear after x-amount of posts (the first is always a reminder to get a quote from classicline )... are you talking about in actual posts? In which case that shouldn't be happening... Unless some image provider is playing silly buggers.
There's a purple "classicline insurance" banner full of moving graphics between the first and second posts of this very thread on my 'puter right now
Okay those are meant to be there, there is a Classicline insurance ad after the first post of every thread (when the thread is over one post long). Then I think there are another one that appears as the page lengthens, position 12 (if memory serves).
The ones that joem83 is seeing don't look like our ads, so may be something to do with the image hosting, but Porsche's avatar is hosted on Proboards and his Signature picture is hosted on Flickr, I guess it could be the flickr thing, but that is a bit odd, also I don't get it on my phone when I look at the same thread.