Can not to edit a page with upfront

Hi,

I can not edit an important page of my webiste with upfront. The page is:

http://magneticaadvertising.com/contactar/

I logg in, I go to the page, I click to "upfront" in the top bar, the upfront editor is loaded but the page is shown as "white" with those "crosses".

I can edit other pages, but not this one.

It is quite critical, because I have to modify this page.

Thanks,
Marcel Odena