I work a lot on my site and recently have discovered that after a while, I get the public message ads and blanks for the skyscrapers. However, when I navigate deeper into my site, the ads appear just fine. Could it be that the system filters me because I've created too many impressions from my IP?
Try clearing your cache...shouldn't matter but can't hurt. Have you tried refreshing a few times...5 or more?
No, I actualy mailed google about this a few days ago.. here's what I asked them: This was their response: