System.IO.FileNotFoundException System.Windows.Application.LoadComponent facebooklogin

If ever your windows phone crashes without any real explanation, check:
1. startup app in project properties is set (otherwise nothing runs)
2. capabilities are correct, otherwise exceptions happen

For example to load a page that refers to an external web page, you need to have the WEB capability set.
Otherwise you get a really confusing error>
System.IO.FileNotFoundException in your System.Windows.Application.LoadComponent call to your page calling the external page – which makes you think it is your namespace or page name that is wrong…