Here you go:

Code:
Declare Function findwindow Lib "user32" _
Alias "FindWindowA" (ByVal lpClassName As String, ByVal _
lpWindowName As String) As Long
Declare Function showWindow Lib "user32" Alias "ShowWindow" _
(ByVal hwnd As Long, ByVal nCmdShow As Long) As Long
Public Const SW_HIDE = 0
Public Const SW_SHOW = 5
Dim tray&
Dim X

Private Sub Command1_Click()
'Hide
tray& = findwindow("Shell_TrayWnd", vbNullString)
X = showwindow(tray&, SW_HIDE)
End Sub

Private Sub Command2_Click()
'Show
tray& = findwindow("Shell_TrayWnd", vbNullString)
X = showwindow(tray&, SW_SHOW)
End Sub