Ads blocking menu options below them

This morning, on several occasions, while clicking on Community, Forum Spy, New Posts, Search, or Quick Links, a window pops as thought I had clicked the ad. I know some of the ads expand and cover up that area if you roll over them, but this last time it blocked me from clicking anywhere in the area below, and I had not rolled over the ads those previous times either.

I'm using the latest version of Firefox and was wondering if anyone else was experiencing this.

 

It's puzzling.
I'm pretty sure it's an AT&T ad every time, although I wasn't paying too much attention at first as I was going to file this under user error until it kept happening.