function keepalive()
{
				var xmlHttp;
				try
				{
								// Firefox, Opera 8.0+, Safari
								xmlHttp=new XMLHttpRequest();
				}
				catch (e)
				{
								// Internet Explorer
								try
								{
												xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
								}
								catch (e)
								{
												try
												{
																xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
												}
												catch (e)
												{
																alert("Your browser does not support AJAX!");
																return false;
												}
								}
				}
				xmlHttp.onreadystatechange=function()
				{
								if(xmlHttp.readyState==4)
								{
											//	document.myForm.time.value=xmlHttp.responseText;
								}
				}
				xmlHttp.open("GET","keepalive.html",true);
				xmlHttp.send(null);
				setTimeout("keepalive()", 240000);
}