[jQuery] AJAX Problem

[dropx]

hi guys,
i am trying to write a simple ajax code with $.ajax() function.
however the Firebug plug-in in Firefox show this error:

[Exception... "'Permission denied to call method XMLHttpRequest.open'
when calling method: [nsIDOMEventListener::handleEvent]"  nsresult:
"0x8057001e (NS_ERROR_XPC_JS_THREW_STRING)"  location: "<unknown>"
data: no]

in the IE it is working there is not any problem.

my code is this:
 var txt = $.ajax({
                        url:"http://../../Posts.xml";,
                        type:"GET",
                        dataType:"xml"
                }).responseText;

i need help. thnks...