window.close(); not working when page changed or refreshed

Question

Hi Everyone,

I have this little function to open/close a popup player:

function popuponclick(popup)
{
  my_window = window.open("folder/player-itself.htm", popup, "width=350,height=150");  
}

function closepopup()
{
  my_window.close();
}

I call the functions from HTML anchors that are on each page of the site (idea is to have the player stopped/started whenever you want)...now...

it works well until i change the page, or refresh the existing one - and from then the window can't be closed anymore. Any idea where i'm wrong? Tested in FF and IE8, same behavior.

Thanks for your help.