I had traced this down initially to an "upgrade" that was made on our back end that nuked what sets of groups were being exposed to these ads and which ones were not. I corrected that and it made sense based on the folks that were complaining about the ads and what groups they were in and which groups were not being excluded for certain ad units.
However, I checked on the groups that you are in and you should not be seeing the ads.
The screen grab is good and that ad should only show up if this type of ad is being displayed (see below). Let me know if you are seeing ads in these locations and if you are, then that at least explains why you are seeing the "floating 728x90" ad unit on the bottom of the page, which if hovered over will expand to the almost full page ad.
Guest are the only group of folks that are supposed to be seeing this type of ad. Members are only supposed to see 4 ads on the page at any one time and those are never supposed to be inline with the forum posts. There should be one 728x90 on the top of the page and one on the bottom of the page. There should be two 300x250's on the right side bar.
If there are 970's or 720's in between posts or topics, then there is something wrong with our system for restricting those types of ads. When I am logged in I don't see them, when I am logged out I do see them. Since this seems to be random, there might be something else going on when our back end was upgraded as I have had these types of ad units in the system for months. The complaints started coming in around the time that part of our backend was upgraded.
Below is a working example of where a normal 970 ad unit would appear (see red circle), but it is being replaced by the ad unit that you see on the top and the bottom of the screen. The part that will help me out tremendously is letting me know if you see that space or an ad in that space in between topics.
The second example is after the first post in a topic. If you see a 728 ad unit there (circled in red), then you also shouldn't be seeing that as you are a logged in member (assuming you are logged in).
LMK if you see either of the indicators of those ad units in between the 1st and 2nd topic and in between the 1st and 2nd post. That will give me something to really troubleshoot. Sorry about this, our goal is NOT to interrupt members experiences on the forum with bothersome ads. We want to encourage non-logged in visitors to become members so they don't see those ads.
In the future we are investigating a mechanism for members to be "ad-free".