Okay, just to reiterate what was already said by Rys, this is definitely not something we put together. We would never do something of the sort.
With that made clear, could you guys to whom this happened post what browser you use (Firefox 1.5/2.0, IE6/7, Opera, Konqueror or Safari).
You may also try to look in your browsing hystory and try to grab the link to the advertisement, if possible. Obviously, it would be also helpful if you could get the redirect link of the adserver (the one you see before being redirected to the advertising page. If you see any redirecting URL that is).