I've been running Adsense since 2003, and this is the first time I've seen this problem. Just in the past month, some of my Adsense ads have been loading slowly -- so slowly, in fact, that they display a blank space and the word, "Loading..." They also display a tiny snippet of text at the bottom of the ad that reads, "Fares found recently. Click for more info." Nothing in the ad is clickable except the word "click." That little snippet of text clues me into the fact that this is one particular advertiser's ads that are having this problem. (Search the text of the snippet and you'll quickly figure out the advertiser.)
My website contains a mix of both Wordpress and static HTML pages; the problem occurs in both environments.
I'm going to try blocking the advertiser to see what happens. Unfortunately, this is a rather large advertiser -- about a third of the ads on my website.
Anyone ever encounter this problem before? Anyone have even the slightest idea what might be going wrong and how to fix it?