I have also faced before this kind of problem but never find out the proper reason behind this.When I had opened that site It redirected in another page.But one reason may be the site was attacked by virus and may be ruined it so the site admin started with another new page and for publicity he used his old site id which is redirected later.
I had suffered many times for this kind of situation.Firstly I had created my profile and then when posted something in forum section it displayed instantly but after few times later when I checked this, it was not there.I am also very eager to know what’s the proper reason behind this? I am very upsate due to this invisibility.