State Management :: Session Mode State Server - Sending Asynchronous Request

Customer were getting "View State Validation Error" due to worker process recycling at our production webserver and to fix that i applied machinekey and then move my Session state Mode from In Proc to State Server to retain session data and not kick out the customer to relogin. I had serialization issue with one object which has to be stored in session but when i moved it out of session i could able to resolve the issue.

But doing all these i was partly successfull in keeping the user in their session when Worker Process recycle event occurs.I was able to refresh the page or make a post back by clicking the refresh button and also able to retain the session values. But the Problem occurs when sending asynchronous request to server which we do periodically every 15 minutes from the moment the user logs in.The web page doesnot update data on website when sending asynchronous request.By Debugging I found at this particular code point it fails to make a postback which is required.

<%=GetHintFromServer%> (When there is no Worker Process recycle i t gets replaced by
WebForm_DoCallback('__Page',message,ShowHint,null,null,false) on postback) Everything works fine when there is no Worker Process Recyling but when it happens looks like sending request asynchronously using javascript fails .Remember When I make a post back by manually clicking submit button everything works fine.

SendRequest(Asynchronous)
function SendRequest(msg, isBusy, chartMsg, vesselMsg)
{
try
{
//confirm("msg"+msg+"isBusy"+isBusy+"chartMsg"+chartMsg+"VesselMsg"+vesselMsg);
_busy = isBusy;
if(chartMsg != null)
{
//confirm("chartMsg"+chartMsg);
_element.SetMessage(true, chartMsg);
}
if(vesselMsg != null)
{
confirm("chartMsg"+vesselMsg);
_element.ShowVesselLoading(true, vesselMsg);
}
_stuckWatchdog = setTimeout( "ClearPendingRequest();", 60000);
var message = msg;
var context = '';
<%=GetHintFromServer%>
}
catch(e)
{
alert( "Exception error on SendRequest(): " + e);
}
}