diff --git a/Global_Indexer/frmIndex.vb b/Global_Indexer/frmIndex.vb
index 87bee1f..63cc71a 100644
--- a/Global_Indexer/frmIndex.vb
+++ b/Global_Indexer/frmIndex.vb
@@ -1901,10 +1901,11 @@ Public Class frmIndex
     End Sub
     Private Sub frmIndex_FormClosing(sender As Object, e As System.Windows.Forms.FormClosingEventArgs) Handles Me.FormClosing
         Try
+            ' This prevents the thread issue when the form containing the viewer is opened via ShowDialog.
+            DocumentViewer1.CloseFile()
             DocumentViewer1.Dispose()
 
             ClassWindowLocation.SaveFormLocationSize(Me)
-            CloseUniversalViewer()
             My.Settings.Save()
         Catch ex As Exception
             ClassLogger.Add(" - Unexpected error in Schliessen des Formulares - Fehler: " & vbNewLine & ex.Message)
@@ -1912,38 +1913,6 @@ Public Class frmIndex
         End Try
 
     End Sub
-    Sub CloseUniversalViewer()
-        Dim workfile = CURRENT_WORKFILE.ToLower
-        If Not workfile.EndsWith("msg") Then
-            CURRENT_HTML_DOC = ""
-            If workfile.EndsWith("pdf") Then
-                DocumentViewer1.CloseFile()
-                My.Settings.SplitterDistance_Viewer = SplitContainer1.SplitterDistance
-            Else
-                Dim pProcess() As Process = System.Diagnostics.Process.GetProcessesByName("Viewer")
-                For Each p As Process In pProcess
-                    p.Kill()
-                Next
-            End If
-
-        Else
-            My.Settings.SplitterDistance_Viewer = SplitContainer1.SplitterDistance
-            Try
-                If File.Exists(CURRENT_HTML_DOC) Then
-                    File.Delete(CURRENT_HTML_DOC)
-                End If
-            Catch ex As Exception
-                ClassLogger.Add(" - Unexpected error in Delete HTML-Doc - Fehler: " & vbNewLine & ex.Message)
-            End Try
-
-        End If
-
-        'If Not IsNothing(DocView) And viewer_string <> "" Then
-        '    DocView.CloseView(viewer_string, 0)
-        'Else
-
-        'End If
-    End Sub
     Private Sub frmIndex_Load(sender As Object, e As System.EventArgs) Handles Me.Load
         ' Abbruchzähler zurücksetzen
         CancelAttempts = 0
@@ -2631,7 +2600,7 @@ Public Class frmIndex
                         If Name_Generieren() = True Then
                             If LogErrorsOnly = False Then ClassLogger.Add(" ...Name_Generieren durchlaufen", False)
                             'Dokumentenviewer ausblenden um keinen Zugriffsfehler zu produzieren
-                            CloseUniversalViewer()
+                            DocumentViewer1.CloseFile()
                             If LogErrorsOnly = False Then ClassLogger.Add(" ...Viewer geschlossen", False)
                             'Die Datei verschieben
                             If Move_File2_Target() = True Then