Along with problems with comments and unwanted CAPTCHA forms, we're seeing some reports about problems with persistent and unwanted interstitial displays, in Blogger Help Forum: Get Help with an Issue . The interstitial display, and its use of cookies, is similar to the new mandatory anonymous comments CAPTCHA form . If your identity can't be determined, or your decision to view a blog can't be remembered, an interstitial warning is displayed - just as the CAPTCHA form is displayed, when your readers are preparing to comment.
What Blogger won't tell you