Apparently, the problem lays in the windows live ID somewhere..
So here i quote:
"Can you please access [url=http://www.windowsphone.com] website, click in my account, register your email address and attempt to download any app using the webpage. Let us know what happens, please.
If that does not help, reset/change your Live ID password https://account.live.com/ResetPassword.aspx
Restart the Windows Phone and try again."