I think that there is no way to solve that problem.
I think the WP intallation is corrupted because I'm having too much errors with plugins.
Some errors that in other WP installations doesn't happen even it have the same plugins.
This are the post about all the errors:
And now I've and incomprehensible issue with All In One Seo Plugin and the image editor (I can't edit some images).
Untill this site I have never experienced too much problems with a WP installation. I will try to re install.
Thanks for your answer.