Maria are you using Internet Explorer? I had a lot of similar problems until I switched my Browser to Mozilla Firefox. I also added the Ad Blocker Plus so I rarely see any ads online now. On the yahoo groups the only ads I see are the ones that show up between messages, and I think that's because they look like messages until you open them. I agree that the new Yahoo isn't as friendly as the old, but I've gotten used to it. For me the whole set up works better in Firefox.
Cari