Big issue on the BO don't save CMS page!

[Massimo100]

Hi all, i have a big problem with prestashop 1.3.6
Yesterday i modified the available languages in BO, path: Back Office >> Tools >> Languages and disabled the unused languages, English spanish and French, left only italian; after that i go to Back Office >> Tools >> CMS, i edit, for example, page about when i save the page after refresh disappear all data in the form and text that i put in page, and two error show in page 1) Meta Title field is required at least in Italiano 2) Rewriting the field link is required at least in Italian.
Another strange error comes when i go to page Back Office >> Tools >> Languages on the bottom and i confirm the default languages is italian, when page refresh comes the error "invalid security key"....
I don't know what can i do.

Any suggestions?

Thanks
Bye
xma