jQuery New release 1.4.2 doesn't suppoert cross server functionality

jQuery New release 1.4.2 doesn't suppoert cross server functionality

Hi,
 
I am using jquery.1.3.2 version in my application.
 
My application is running on two different server, one is on "http" and other is on "https"
 
I am displaying few files from https server to http server via ajax. Everything works fine in IE 6 +.
 
But same functionality not works in Firefox 3.5.
 
Before changing jQuery's version (dont know exactly which version), my functionality works properly in IE and FF.
 
Today I downloaded latest version of Jquery (1.4.2), and while testing I found that, my functionality is not working in IE too. After restoring old version (1.3.2) everything works fine (in IE)
 
Does anybody explain me what I am doing wrong? What is the solution for this?
 
Regards,
 
Vikas Parab