Javascript Error after using Script Manager- : The message received from the server could not be parsed-Collection of common programming errors

I am opening a ShowModalDialog on a button OnClientClick event and the javascript for it is:-

 function openmodalWinLunch() { var variable1 = "Lunch"; window.showModalDialog("ClockPopUP.aspx?code=" + variable1, "dialogWidth:290px;dialogHeight:270px,"); }

On the Clock.aspx page i have a asp button on which i had written code :-

protected void btnStop_Click(object sender, EventArgs e) { _nonProduction = new NonProduction(); if (Session["LastNonProdTimeID"] == null) { } else { int NonProdTimeEntryID = Convert.ToInt32(Session["LastNonProdTimeID"]); isTimeSpentUpdated = _nonProduction.UpdateTimeSpentInDB(NonProdTimeEntryID); if (isTimeSpentUpdated == true) {
  string timespent = Convert.ToString(_nonProduction.GetTimeSpent(NonProdTimeEntryID)); Response.Write("window.close();"); Response.End();
  } else
            {
            }
        }
    }

Previously every thing is working fine and this code is working as per my requirement. Just i had added Scriptmanager on the Clock.aspx as i m showing a clock which shows the elapsed time to the user. After that when i m clicking on the btn_Stop on CLock.aspx page i am getting this error message:-“Microsoft JScript runtime error: Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed.”   Please guide me that how i solve this issue.  

I found that what is the root cause of this error. It is happening because i m using Resonse.Write and other information is Here

 

Guide me that how i fix this as i want to close the webpage after button click event.