function SetCookie(obligar) {
    document.cookie = 'PHPRes='+screen.width + 'x' + screen.height;
    if (obligar == 1 && document.cookie != '')
        document.location.href=document.location.href;
}
function ChequearResolucion(ancho, alto) {
    if(ancho != screen.width && alto != screen.height) {
        SetCookie();
    }
}