Error when putting an "article" sometimes

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I'm using articles to put some walkthroughts in my website, and this happens sometimes. But in most part of time, everything goes ok, nothing wrong happens.
I'm putting my "article" here, i don't know, and this happens not only with one article, but i don't have any idea what has been causing this!
Please, help me...this is very important for my website!
See ya!