window.open()在IE6和IE7中不工作

我有一个dotnet应用程序，我必须关闭当前窗口，然后在运行时再次打开新窗口。我使用了Javascript。代码如下:

function OpenNewWindow() {
    if (ConfirmStartTest()) {
        closeWindow();
window.open("OnlineTestFrame.aspx", "_Parent", "model=yes,dailog=no,top=0,height=screen.height,width=screen.width,status=no,toolbar=no,menubar=no,location=no,zoominherit =0,resizable =no,scrollbars=yes,dependent=no,directories=no,taskbar=no,fullscreen=yes");
        self.focus();
    }
}
//taking the confirmation for starting test
function ConfirmStartTest() {
    var result = confirm("Do you want to start the test now?");
    return result;
}
//function to close the current window
function closeWindow() {
     //var browserName = navigator.appName;
     //var browserVer = parseInt(navigator.appVersion);
     var ie7 = (document.all && !window.opera && window.XMLHttpRequest) ? true : false;  
     if (ie7) 
           {     
           //This method is required to close a window without any prompt for IE7
           window.open('','_parent','');
           window.close();
           }
     else 
           {
           //This method is required to close a window without any prompt for IE6
           this.focus();
           self.opener = this;
           self.close();
           }
}

现在，当我在IE7和IE6中运行这个应用程序时，它没有运行。但是，在IE8中它运行得很好。

此代码在以前的所有IE6和IE7中都可以正常工作。突然就产生了误差。它不能打开新窗口并在b/w中突然停止。