Dim FileName As String
        Dim swr As StreamWriter
        FileName = "d:\Err.log"
        If Not File.Exists(FileName) Then
            File.CreateText(FileName).Close()
        End If
        swr = New StreamWriter(FileName, True, _
          System.Text.Encoding.ASCII.Default)
        swr.WriteLine("Beliebiger Text")     ' Hier kommt der Fehler 
        swr.Close()