problem with linked documents on homepage

Hi, i have some problems when inserting media on the Front page. I would like to have an link directly to the file, but always get an link to an page with a link to the document (Even if i choose File Url).

This only occurs on the page set to Front page, on all other pages it works fine, but if I change them to front page, an inserted media always becomes an link to an page

I have tried with different Themes, but the result is the same.

One clue is that inserted media on Front page always get an rel-alternative ( a rel=’attachment wp-att-570′ …. )

Regards