Some improvements...

Vocaluxe/Base/CBackgroundMusic.cs

@@ -333,6 +333,12 @@ namespace Vocaluxe.Base
             Play();
         }
 
+        public static void StopPreview()
+        {
+            _PreviewPlayer.Close();
+            _PlaysPreview = false;
+        }
+
         /// <summary>
         ///     (Re-)Starts the _CurrentPlaylistElement
         /// </summary>

Vocaluxe/Base/CMain.cs

@@ -395,6 +395,11 @@ namespace Vocaluxe.Base
             CBackgroundMusic.PlayPreview(start);
         }
 
+        public void StopPreview()
+        {
+            CBackgroundMusic.StopPreview();
+        }
+
         public CTexture GetVideoTexture()
         {
             return CBackgroundMusic.GetVideoTexture();

VocaluxeLib/IBasic.cs

@@ -135,6 +135,7 @@ namespace VocaluxeLib
 
         void LoadPreview(CSong song, float start = 0f);
         void PlayPreview(float start = -1f);
+        void StopPreview();
 
     }
 

VocaluxeLib/Menu/SongMenu/CSongMenuFramework.cs

@@ -500,7 +500,9 @@ namespace VocaluxeLib.Menu.SongMenu
 
         private void _PlaySong(int nr)
         {
-            _ResetPreview();
+            _PreviewNrInternal = -1;
+
+            CBase.BackgroundMusic.StopPreview();
 
             CSong song = CBase.Songs.GetVisibleSong(nr);
             if (song == null)

VocaluxeLib/Songs/CSong.cs

@@ -458,7 +458,10 @@ namespace VocaluxeLib.Songs
             if (Preview.Source == EDataSource.None)
             {
                 if (Medley.Source != EDataSource.None)
+                {
                     Preview.StartTime = CBase.Game.GetTimeFromBeats(Medley.StartBeat, BPM);
+                    Preview.Source = EDataSource.Calculated;
+                }
             }
         }
 

VocaluxeLib/Songs/CSongLoader.cs

@@ -416,7 +416,7 @@ namespace VocaluxeLib.Songs
                     {
                         //PreviewStart is not set or <=0
                         _Song.Preview.StartTime = (headerFlags & EHeaderFlags.MedleyStartBeat) != 0 ? CBase.Game.GetTimeFromBeats(_Song.Medley.StartBeat, _Song.BPM) : 0f;
-                        _Song.Preview.Source = EDataSource.Calculated;
+                        _Song.Preview.Source = _Song.Preview.StartTime == 0 ? EDataSource.None : EDataSource.Calculated;
                     }
 
                     if ((headerFlags & EHeaderFlags.MedleyStartBeat) != 0 && (headerFlags & EHeaderFlags.MedleyEndBeat) != 0)