Just know I posted the 1st post on a new page of a thread. Then I edited it for spelling mistakes. After pressing save I was returned to the new page but it was empty. I had to refresh the page to see my post.

I also pressed the 'Go Advanced' button while editing and got this message:

Este fichero XML no parece tener ninguna información de estilo asociada. Se muestra debajo el árbol del documento.
<error>
Your submission could not be processed because a security token was missing.<br />
<br />
If this occurred unexpectedly, please <a href="sendmessage.php">inform the administrator</a> and describe the action you performed before you received this error.
</error>

EDIT:
When editing this post, to add the XML error this post also 'dissapeared' after pressing save. Had to refresh the page to see it. Seems to only happen to the one editing.