Popup Window will not Close

Answer 1

You may have a collision in the names. You have a variable PopupWnd and the name of the window PopupWnd.

var PopupWnd = null; function
ShowPopup(){
     PopupWnd = window.open('Popup.aspx','PopupWindow','');
} 
function HidePopup(){
    if(PopupWnd != null){
        if(!PopupWnd.closed){
            PopupWnd.close();
        }
    }
 }

That should work as the WindowName no longer collides with the variable. I'd suggest checking out http://www.infimum.dk/HTML/JSwindows.html for a more indepth view on window manipulation using javascript.

In a case like this, I'd also suggest Line by Line testing and doing things such as throwing out an alert i.e. do an alert after if PopupWnd != Null to see if it even reaches that part. Hell, do an alert right at th ebeginning of the HidePopup function to see what the value of PopupWnd is...