Odd Ajax issue

I have an application that uses jQuery v1.8.3, jQuery UI 1.8.16 and jqGrid 4.4.1 plus some extensions that I created. Yesterday I upgraded to jQuery UI 1.9.2

Immediately I encountered some erratic behavior with Ajax calls. About 30% of Ajax requests would fetch the requested page then reload the main page inside itself. I cannot see any pattern to this behavior. All the Ajax requests are initiated by this code in the main page.

function GetContent(pg){

$('#PlsWait').removeClass('ui-helper-hidden');

$('#ajaxerror').html('');

$('#pagecontent').load(pg,function(resp,status,xhr){

if(status=='error'){

var msg='Sorry but there was an error: ';

$('#ajaxerror').html(msg+xhr.status+' '+xhr.statusText);

}

});

}

All of the URL's follow the same format:

GetContent('http://192.168.0.101/cgi/loadpage.pl?RQ=XXXX&ID=100')

The only difference is XXXX which changes according to the request.

I tried removing the extensions that I created,using JQuery UI with all components and with a minimum of components required to run the app. Nothing made any difference. Changing back to jQuery UI 1.8.16 immediately cured the problem. I'm totally at a loss to see why this strange behavior happens or what exactly is causing it.