OK Guys I have narrowed it down It is not the fact that the ajax requests are nested, it is down to the format of the JSON string in the data: block
I narrowed the example down to something really simple $.ajax({ type: "POST", data: '{"name":"dave"}', url: "WebServices/KayakService.asmx/testMethod", beforeSend: function(xhr) { xhr.setRequestHeader("Content-type", "application/json; charset=utf-8"); }, dataType: "json", success: function(msg) { alert('success'); }, error: function(msg) { alert('failed'); } }); IE doesnt like the data block at all and always fails without even hitting the web service. Dannster