If you log into that page without going through the router, would there be an ad in that place?
Maybe they are doing what I am doing: Have a bunch of the crappy ad serving DNS addresses setup to resolve to 127.0.0.1. End result is I get a lot of pages with boxes showing “Not Found” with some seemingly arbitrary file path. Its not found because it isn’t on my computer.
Why do I do that? I hate ads, I don’t want ads to track me, I don’t want to slow down my web browsing for a slow ad web server to respond and I am not overly fond of Flash which a huge number of ads are built with.
You can check that by showing the source for pages that do that, see what URL the “Not Found” areas are trying to reach then doing a nslookup or dig on the DNS address portion of the URL and see what IP address is returned.