Runtimeerror 1004

Private Sub CommandButton1_Click()
Dim c As Range
Dim d As String
If ComboBox1.Value = "" Then
MsgBox "Bitte User auswählen!"
Exit Sub
End If
Set c = Sheets("Passwörter").Range("A:A").Find(ComboBox1.Value)
If c Is Nothing Then
MsgBox "User ist nicht registriert"
ComboBox1.Value = ""
TextBox2.Value = ""
Else
d = TextBox2.Value
d = StrConv(d, vbLowerCase)
If d = c.Offset(0, 1) Then
Dim datei As String
Const Lw = "E:\"
Const Pfad = "Q:\Pfad"
Select Case c
Case "D13"
datei = "dok1.xls"
ChDrive Lw
ChDir Pfad
On Error Resume Next
Workbooks.Open Filename:=datei, Password:="xxx"
Case "C37"
datei = "dok2.xls"
ChDrive Lw
ChDir Pfad
On Error Resume Next
Workbooks.Open Filename:=datei, Password:="xxx"
End Select
Me.Hide
Else
MsgBox "Falsches Passwort"
TextBox2.Value = ""
End If
End If
End Sub

Private Sub Workbook_BeforeClose(Cancel As Boolean)
ActiveWorkbook.Protect Password:="xxx"
End Sub

Private Sub Workbook_Open()
'ActiveWorkbook.Unprotect Password:="xxx"
Sheets("navigation").Activate
With ActiveWindow
.DisplayWorkbookTabs = True
End With
Dim Tabz As Integer
Dim i As Integer
Application.ScreenUpdating = False
'Sheets("navigation").Select
Tabz = ActiveWorkbook.Sheets.count
For i = 1 To Tabz
Sheets(i).Protect DrawingObjects:=True, Contents:=True, _
Scenarios:=True, Password:="masahiro"
Sheets(i).Activate
Application.ActiveWindow.Zoom = 60
Next i
Application.ScreenUpdating = True
Sheets("navigation").Select
End Sub