[jQuery] Json post with mozilla

[Nowhere]

Hi all,
I'm newbie to Jquery so excuse me for dummy question.
I'm facing with the issue of making a call to another domain with
mozilla firefox. When I need a GET request, I use JQuery.getJson and
it works fine. The problem is when I need to do a POST request, I
tried with:

jQuery.post(
                url ,
               dati ,
               function(data){
                alert(data);
                ....
}, "json" );

but it gives me following error:

Errore: uncaught exception: [Exception... "Access to restricted URI
denied"  code: "1012" nsresult: "0x805303f4 (NS_ERROR_DOM_BAD_URI)"
location: "http://localhost:8081/html/js/barebone.jsp?
browserId=firefox&themeId=classic&colorSchemeId=01&minifierType=js&minifierBundleId=javascript.barebone.files&minifierBundleDir=
%2Fhtml%2Fjs&t=1233649818000 Line: 1"]

The same error I get making a not json GET request. In this case I
solved using json...but in POST case I don't know how proceed.
Any hint will be appreciated, it's very urgent for me. If you need
more info let me know.
Greetings.