FormsAuthentication.SetAuthCookie loosing User.Identity.Name

We are logging in users via FormsAuthentication.SetAuthCookie

User.Identity.IsAuthenticed then becomes true and the User.Identity.Name is w/e we provided to the SetAuthCookie method.

As time goes by, or you close the browser, Use开发者_如何学运维r.Identity.Name get's lost yes IsAuthencticated is still true.

Any ideas?