Steps to reproduce:
1. Add the blogs portlet to a page, add a blog entry and log out.
2. As a guest user, you can comment the blog entry. When you try to publish it will ask you to introduce your name, email and captcha.
3. Add your liferay email address (the one with numbers: firstname.lastname@example.org)
4. You will get this error: "The friendlyURL may conflict with another page"
Instead, it should just post the message.
(This is happening because we are creating an inactive user in the background, but the screenname can not contain only numbers. We should validate this ourselves in the server and generate a valid screenname instead of showing the error).