Is it possible to enable or disable xmlHTTP object from Browser?

In Mac OS, Fire fox Version 3.6.3 is blocking XMLHttp Object in one machine but it didn't block in same set of OS开发者_开发问答 and browser versions in other machine. Is there any way to enable or disable xmlhttp from browser?

XMLHttpRequest, like any other JavaScript interface, can be blocked in Firefox using CAPS preferences (capability.policy.default.XMLHttpRequest).

But it's highly unlikely that this has been done. (There is no UI for it.) I suspect you have a different problem.