Imports System.IO
 
Public Class Form1
  Dim strSelItem As String 
  Dim intTypArr(,) As String
 
  Const WM_DEVICECHANGE As Integer = &H219
  Const DBT_DEVICEARRIVAL As Integer = &H8000
  Const DBT_DEVICEREMOVECOMPLETE = &H8004
 
  Public Class TreeNode
    Inherits System.Windows.Forms.TreeNode
    Public Path As String
  End Class
 
  Public Declare Function LockWindowUpdate Lib "user32.dll" (ByVal hWndLock As _
    IntPtr) As Boolean  '???
 
 
Protected Overloads Overrides Sub WndProc(ByRef msg As Message)
  MyBase.WndProc(msg)
  If msg.Msg = WM_DEVICECHANGE AndAlso msg.WParam = CType(DBT_DEVICEARRIVAL, _
    IntPtr) Then
    frmInfo.TextBox1.Text = vbNewLine & "neuen Datenträger erkannt"
    frmInfo.intTime = 1
    frmInfo.Show
    Call setDrives()
    cbDrives.SelectedItem = strSelItem 
    strSelItem = Me.cbDrives.SelectedItem
  End If
  If msg.Msg = WM_DEVICECHANGE AndAlso msg.WParam = CType( _
    DBT_DEVICEREMOVECOMPLETE, IntPtr) Then 
    frmInfo.TextBox1.Text = vbNewLine & "Datenträger wurde entfernt"
    frmInfo.intTime = 1
    frmInfo.Show 
    Call setDrives()
    If InStr(strSelItem, "E:") Then
      cbDrives.SelectedIndex = 0
      strSelItem = Me.cbDrives.SelectedItem
      Call setFolders(strSelItem.Substring(strSelItem.Length-3, 2) & "\")
      trvFolders.Focus
    Else
      cbDrives.SelectedItem = strSelItem
    End If
  End If
  End Sub
 
 
Private Sub Me_Load(sender As Object, e As System.EventArgs) Handles Me.Load
  Call setDrives()
  cbDrives.SelectedIndex = 0
  strSelItem = Me.cbDrives.SelectedItem
  Call setFolders(Directory.GetLogicalDrives.First)
End Sub
 
 
 
Private Sub cbDrives_DrawItem (ByVal sender As Object, ByVal e As _
  System.Windows.Forms.DrawItemEventArgs) Handles cbDrives.DrawItem
  If Me.cbDrives.DroppedDown = True AND (e.State And DrawItemState.Selected) = _
  DrawItemState.Selected Then
    e.Graphics.FillRectangle(SystemBrushes.Control, e.Bounds)
  Else
    e.Graphics.FillRectangle(SystemBrushes.Window, e.Bounds)
  End If
 
  If intTypArr Is Nothing Then Exit Sub
 
  e.Graphics.DrawImage(ImageList2.Images.Item(CInt(intTypArr(e.Index,1))), 4, _
    e.Bounds.Top + 1)
  e.Graphics.DrawString(cbDrives.Items(e.Index).ToString, cbDrives.Font, _
  Brushes.Black, 20, e.Bounds.Top + 1)
  End Sub
 
Private Sub cbDrives_DropDownClosed (sender As Object, e As System.EventArgs) _
  Handles cbDrives.DropDownClosed
  Me.trvFolders.Nodes.Clear
  strSelItem =  Me.cbDrives.SelectedItem
  Call setFolders(strSelItem.Substring(strSelItem.Length-3,2) & "\")
  trvFolders.Focus
End Sub
 
Private Sub setFolders(strLW As String)
  Dim tn As TreeNode = Nothing
  Dim nodeInfo As DirectoryInfo = New DirectoryInfo(strLw)
 
  Try
    trvFolders.Nodes.Clear
    For Each di As DirectoryInfo In nodeInfo.GetDirectories
      If di.Attributes = FileAttributes.Directory Then
        tn = AddNode(trvFolders.Nodes, di.Name, di.FullName)
        If My.Computer.FileSystem.GetDirectories(tn.Path).Count > 0 Then 
          AddNode(tn.Nodes, ".", ".")
        End If
      End If
    Next
 
  Catch ex As Exception
  End Try
  End Sub
 
Private Function AddNode (ByVal nodeCollection As TreeNodeCollection, ByVal _
  Caption As String, ByVal path As String) As TreeNode
  Dim tn As New TreeNode()
 
  tn.Text = Caption
  tn.Path = path
  nodeCollection.Add(tn)
  Return tn
End Function
 
End Class

Private Sub setDrives()
  Try
    Erase intTypArr
    cbDrives.Items.Clear
    ReDim Preserve intTypArr(DriveInfo.GetDrives.Length - 1, 1)
 
    Dim i As Integer = 0
    For Each d As DriveInfo In DriveInfo.GetDrives 
      Select Case d.DriveType
        Case DriveType.Unknown
          intTypArr(i,0) = " Unknown (" & d.Name.Substring(0, 2) & ")"
          intTypArr(i,1) = "1"
        Case  DriveType.Fixed
          If Asc(d.Name.Substring(0,1)) > 68 Then
            intTypArr(i,0) = " " & d.VolumeLabel & " (" & d.Name.Substring(0, _
              2) & ")"
            intTypArr(i,1) = "4"
          Else
            intTypArr(i,0) = " Laufwerk (" & d.Name.Substring(0, 2) & ")"
            intTypArr(i,1) = "3"
          End If
        Case DriveType.Network
          intTypArr(i,0) = " Netzlaufwerk (" & d.Name.Substring(0, 2) & ")"
          intTypArr(i,1) = "4"
        Case  DriveType.CDRom
          If d.IsReady = False Then Continue For
          intTypArr(i,0) = " DVD-RW-Laufwerk (" & d.Name.Substring(0, 2) & ")"
          intTypArr(i,1) = "5"
        Case DriveType.Ram
          intTypArr(i,0) = " Ram (" & d.Name.Substring(0, 2) & ")"
          intTypArr(i,1) = "5"
        Case  DriveType.Removable
          If d.IsReady = False Then Continue For 
          intTypArr(i,0) = " " & d.DriveType.ToString & " (" & d.Name.Substring( _
            0, 2) & ")"
          If d.Name = "A:\" OR d.Name = "B:\" Then
            intTypArr(i,1) = "2"
           Else
            intTypArr(i,1) = "6"
          End If
      End Select      
 
      Me.cbDrives.Items.Add(intTypArr(i,0))
      i += 1
    Next
 
  Catch ex As Exception
    MsgBox("Fehler: " & ex.ToString, MsgBoxStyle.Information, "Fehler in" & _
      "'setDrives()'")
  End Try
End Sub

 If msg.Msg = WM_DEVICECHANGE AndAlso 
    msg.WParam = CType(DBT_DEVICEREMOVECOMPLETE, IntPtr) Then
 
    Call setDrives()
 
    If cbdrives.Items.Contains(strSelItem) Then
       If InStr(strSelItem, "E:") > 0 Then
          '???????????
          cbdrives.SelectedIndex = 0
          strSelItem = Me.cbdrives.SelectedItem.ToString            
       Else
          'Das in der Combo gewählte Item ist noch vorhanden
          cbdrives.SelectedItem = strSelItem
       End If
    Else
       'Das in der Combo gewählte Item ist entfernt worden
       cbdrives.SelectedIndex = 0
       strSelItem = cbdrives.SelectedItem.ToString                
    End If
 End If

Protected Overloads Overrides Sub WndProc(ByRef msg As Message)
  MyBase.WndProc(msg)
 
  If msg.Msg = WM_DEVICECHANGE AndAlso msg.WParam = CType(DBT_DEVICEARRIVAL, _
    IntPtr)
    LockWindowUpdate(CType(0, System.IntPtr))
    If cbDrives.DroppedDown = True Then
      cbDrives.DroppedDown = False
      Call setDrives()
      cbDrives.DroppedDown = True
    Else
      Call setDrives()
    End If
 
    cbDrives.SelectedItem = strSelItem
    LockWindowUpdate(CType(0, System.IntPtr))
  End If
 
  If msg.Msg = WM_DEVICECHANGE AndAlso msg.WParam = CType( _
    DBT_DEVICEREMOVECOMPLETE, IntPtr) Then
    LockWindowUpdate(CType(Me.Handle.ToInt32, System.IntPtr))
 
    If cbDrives.DroppedDown = True Then
      cbDrives.DroppedDown = False
      Call setDrives()
      cbDrives.DroppedDown = True
    Else
      Call setDrives()
    End If
 
    If cbDrives.Items.Contains(strSelItem) Then
      cbDrives.SelectedItem = strSelItem
    Else
      frmInfo.TextBox1.Text = "Das aktuell angezeigte Laufwerks wurde entfernt"
      frmInfo.intTime = 1
      frmInfo.Show
 
      cbDrives.SelectedIndex = 0
      strSelItem = cbDrives.SelectedItem.ToString
      Call setFolders(strSelItem.Substring(strSelItem.Length-3,2) & "\")
      LockWindowUpdate(CType(0, System.IntPtr))
    End If
  End If
End Sub

Imports System
Imports System.IO
Imports System.Management 'Verweis auf Assembly System.Management.DLL ist 
' erforderlich !!!! 
 
Public Class frmDrives2
 
    Dim WithEvents watcher As New ManagementEventWatcher
 
    Dim lstdrives As New List(Of String)
    Dim bsDrives As New BindingSource With {.DataSource = lstdrives}
    Dim WithEvents cboDrives As New ComboBox With
        {.Parent = Me, .Width = 200, .Left = 5, .Top = 5,
        .DropDownStyle = ComboBoxStyle.DropDown, .DataSource = bsDrives}
 
    Dim SelectedDrive As String = ""
 
 
    Public Enum USBAction
        inserted = 2
        removed = 3
    End Enum
 
 
    Private Sub frmDrives2_Load(sender As Object, e As EventArgs) Handles _
      MyBase.Load
 
        FillDrivelist()
 
        Dim query As WqlEventQuery = New
        WqlEventQuery("SELECT * FROM Win32_VolumeChangeEvent WHERE EventType =" & _
          "2 or EventType = 3")
 
        watcher.Query = query
        watcher.Start()
 
    End Sub
 
 
    Private Sub watcher_EventArrived(sender As Object, 
        e As EventArrivedEventArgs) Handles watcher.EventArrived
 
        Dim et As Short = CShort(e.NewEvent.Properties("EventType").Value)
        Dim driveName As String = e.NewEvent.Properties( _
          "DriveName").Value.ToString
        Dim eventName As String = [Enum].GetName(GetType(USBAction), et)
 
        If et = USBAction.inserted Then
            For Each drv As DriveInfo In IO.DriveInfo.GetDrives
                If drv.Name.StartsWith(driveName) Then
                    lstdrives.Add(driveName & "  " & drv.DriveType.ToString)
                End If
            Next drv
            lstdrives.Sort()
        Else
            For i As Integer = lstdrives.Count - 1 To 0 Step -1
                If lstdrives(i).StartsWith(driveName) Then lstdrives.RemoveAt(i)
            Next i
        End If
 
        cboDrives.Invoke(New MethodInvoker(AddressOf SetDriveBinding))
    End Sub
 
 
    Private Sub SetDriveBinding()
        bsDrives.ResetBindings(False)
        SetSelectedDrive()
    End Sub
 
 
    Private Sub FillDrivelist()
        lstdrives.Clear()
 
        For Each drv As DriveInfo In IO.DriveInfo.GetDrives
            lstdrives.Add(drv.Name & " " & drv.DriveType.ToString)
        Next drv
        lstdrives.Sort()
        bsDrives.ResetBindings(False)
    End Sub
 
 
    Private Sub SetSelectedDrive()
        Dim found As Boolean
        If String.IsNullOrEmpty(SelectedDrive) Then Exit Sub
        If lstdrives.Count = 0 Then Exit Sub
 
        For i As Integer = 0 To lstdrives.Count - 1
            If lstdrives(i).StartsWith(SelectedDrive) Then
                cboDrives.SelectedIndex = i : found = True
            End If
        Next i
        If Not found Then cboDrives.SelectedIndex = 0
    End Sub
 
 
    Private Sub cboDrives_SelectedIndexChanged(sender As Object,
                e As EventArgs) Handles cboDrives.SelectedIndexChanged
        If cboDrives.SelectedItem Is Nothing Then
            SelectedDrive = ""
        Else
            SelectedDrive = cboDrives.SelectedItem.ToString
        End If
    End Sub
End Class

    Private Sub SetDriveBinding()
        bsDrives.ResetBindings(False)
        Dim droppeddown As Boolean
        With cboDrives
            If .DroppedDown Then
                'Dropdown ggf. schließen
                .DroppedDown = False
                droppeddown = True
            End If
        End With
        SetSelectedDrive(droppeddown)
    End Sub
 
 
    Private Sub SetSelectedDrive(droppeddown As Boolean)
        Dim found As Boolean
        If String.IsNullOrEmpty(SelectedDrive) Then Exit Sub
        If lstdrives.Count = 0 Then Exit Sub
 
        For i As Integer = 0 To lstdrives.Count - 1
            If lstdrives(i).StartsWith(SelectedDrive) Then
                cboDrives.SelectedIndex = i : found = True
            End If
        Next i
        If Not found Then cboDrives.SelectedIndex = 0
 
        'Dropdown ggf. wieder öffnen 
        cboDrives.DroppedDown = droppeddown
    End Sub