Ho 07, I see there are problems. On the REPARACIONES page there are two forms. If I submit the one on the left the page tells me the form has been submitted then disappears but the top slider height is reduced and the menu disappears. The form on the right acts similarly but the slider remains the same height but the menu disappears. Without seeing your xar file I wouldn't like to say what exactly is causing it. Firstly try the forms on their own dedicated page. Do they work correctly on this? I suspect it's the form. On completion the reply height of the form is far smaller than the fill-in section which is causing this issue within the placeholder.

As an aside I dislike the mouse-over effect opening your pages rather than an on click opening.