Hm, actually I uploaded again main theme, without any modification and checked it with the validator. I dont know if its the cache or the theme have some problems, but still appearing 42 erros, 3 warinings.
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Ok, now I desactivated all the plugins and the theme is again normal. Time to see which plugin is making the theme crash.
I find out, sadly was Shortcodes Ultimate plugin. Oh, I closed bad the tags, that caused the crash. Solved