I saw a message on the Ning Creators today about a Vivian being banned. When you ban someone all of the comments and postings of the bannee are deleted from Ning. She must have posted the comment and then was banned before you were able to read the comment.;
DoonePlace is exactly right. Vivian posted a number of comments today and a couple of members alerted me that she was "spamming" them. I looked at her profile and quickly determined to "ban" her (Ning's terminology for removing a member). When you ban a member, it removes all of his or her content, and so that's why you couldn't find anything when you clicked through from the email notification.