Question

i have a problem with a WP7 app. I want that a user can login into the application, doing some stuff and logout.

Now, then a new user get the phone, it should not be possible to get into the session of the old user (by simply pressing back until the user see the intern data of the previous user who was logged in).
how to make this?

The best thing would be, that when a user press the back button, it will be forwared to the first page of the app. the problem then is, that there will be a loop and the app will not pass the certification because it will not be possible to exit it.

Here is an overview:

loginPage (no return just exiting the app) -> internPage (possibility to logout and return to loginPage)

Answer 1

You can clear the back stack using NavigationService.RemoveBackEntry:

while (this.NavigationService.BackStack.Any())
{
    this.NavigationService.RemoveBackEntry();
}

Put this in the OnNavigatedTo of your LoginPage, so pressing back on this page will exit the application. If the LoginPage is the first page the user sees when launching the app (and therefore is the application main page), it should pass certification.