To disable an UltraWebGrid client-side, use the following (remember that
Javascript is casE sensitivE):

    function DisableGrid()
    {
       var grid = igtbl_getGridById("UltraWebGrid1");
       grid.Element.disabled=true;
    }

Server-side:

    UltraWebGrid1.DisplayLayout.AllowUpdateDefault =
       Infragistics.WebUI.UltraWebGrid.AllowUpdate.No