Open Question: Windows 7 Media Player 11 looses Listed Movie Files?

Hi, Has anyone else experienced the lose of added files to Windows 7 Media Player 11? I was just editing my movie files listed in Windows 7 Media Player 11 when all of a sudden it stopped working on me and when it restarted my movie files were unlisted??? Do you know how frustrating that is!!! Why does this happen and how can it be fixed??? Also, I'm trying to "add" new libraries to separate the movies, business and what not from Video files in order to keep it simpler. I've added libraries in the folders view but these new "Libraries" will not appear in the Windows media Player!!!??? I've clicked on other libraries in the media player and highlighted "Show Other Libraries" but they still won't show. Why is this and how do you fix it. Thanks. John