Nope. Don't see anything on my page that could affect it. Double-checked everything I could think of.
And I only see it with one advertiser. All other ads are fine, but when this one comes up, it's a 160x600 flash unit shown in a 728x90 ad panel.
I also have a 160x600 panel on some pages, but not on all of them. This problem exists both kinds of pages, which that contain 160x600 unit in addition to the 728x90 and those that don't.
Just tried to contact AdSense for the first time in years. Now I understand the frustration of publishers.
Reading other comments, I knew it was bad, but this bad?
Not only does there seem to be no way to contact them, but they also make you waste a huge amount of time before you realize that.