I have had some wierd missing zone stamp issues as well, but I think it had to do with converting an old template file. Have you started a "new" project or have you opened an existing project? Go to your zone tool and open the default settings and see if the stamp is missing. You might also play with attribute manager and overwirte your zones if there are not ones in place that you are using. I was a little surprised at the error I had since there were no zones placed in the project.