Duplicate or Multiple Playlists and Songs in Windows Media Player

I have Windows Vista Ultimate, Windows Media Player 11, ver. 11.0.6000.6344.
When I pull up my Playlists view, ALL of my playlists are listed 2, 3 and
sometimes even 4 times. The same is true when I pull up my Songs view. All
these duplicates continue to make Media Player slow, sluggish and ALWAYS,
ALWAYS "Not Responding." If I wait long enough, sometimes up to 5 minutes,
the Media Player will start responding again.
The Playlists are listed in my Users/<user name>/music/playlists; but they
are also listed in Network/<computer name>/<user name/music/playlists.
I tried deleting all the playlists from each folder separately, but erasing
them in one folder erases them in the other folder, so I'm left with nothing.
Any feedback on how to remedy this problem?