These are very common on social networking sites, especially involving browser-based games such as those created by Zynga.
The purpose of a White Page of Death is usually to indicate a failure of communication among the client input (you), the main site's server, and the game site's server.
Or, in the case of a social site's own server failure, to inform you that the server is broken and can't find your information.
2. Typical MySpace White Page of Death:
"Oops! An error has occurred. Please forward this to the MySpace tech team."