Dim bOK2Use As Boolean

Private Sub btnOK_Click()
    Dim bError As Boolean
    Dim sSName As String
    Dim p As DocumentProperty
    Dim bSetIt As Boolean

    bOK2Use = False
    bError = True
    If Len(txtUser.Text)  0 And Len(txtPass.Text)  0 Then
        bError = False
        Select Case txtUser.Text
            Case "user1"
                sSName = "Corp"
                If txtPass.Text < "u1pass" Then bError = True
            Case "user2"
                sSName = "Elect"
                If txtPass.Text < "u2pass" Then bError = True
            Case Else
                bError = True
        End Select
    End If
    If bError Then
        MsgBox "Invalid User Name or Password"
    Else
        'Set document property
        bSetIt = False
        For Each p In ActiveWorkbook.CustomDocumentProperties
            If p.Name = "auth" Then
                p.Value = sSName
                bSetIt = True
                Exit For
            End If
        Next p
        If Not bSetIt Then
            ActiveWorkbook.CustomDocumentProperties.Add _
              Name:="auth", LinkToContent:=False, _
              Type:=msoPropertyTypeString, Value:=sSName
        End If

        Sheets(sSName).Visible = True
        Sheets(sSName).Unprotect (txtPass.Text)
        Sheets(sSName).Activate

        bOK2Use = True
        Unload UserForm1
    End If
End Sub

Private Sub UserForm_Terminate()
    If Not bOK2Use Then
        ActiveWorkbook.Close (False)
    End If
End Sub