A propper fix can be found here: http://zacster.blogspot.com/2008/10/jquery-ie7-load-url-problem.html
I have use Tim Boormans Fix & Fuction.
function unique_requestid() {
var timestamp = Number(new Date()).toString();
var random = Math.random() * (Math.random() * 100000 * Math.random() );
var unique = new String();
unique = timestamp + random;
return unique;
}
$('#Your_Element_ID').load("/ajaxpage.php?a=get_something&random=" + unique_requestid());