Código:

Option Explicit
Private Declare Function ShowWindow _
 Lib "user32" _
 (ByVal hwnd As Long, _
 ByVal nCmdShow As Long) As Long


Private Declare Function FindWindow _
 Lib "user32" _
 Alias "FindWindowA" _
 (ByVal lpClassName As String, _
 ByVal lpWindowName As String) As Long
 
Private Declare Function FindWindowEx _
 Lib "user32" _
 Alias "FindWindowExA" _
 (ByVal hWnd1 As Long, _
 ByVal hWnd2 As Long, _
 ByVal lpsz1 As String, _
 ByVal lpsz2 As String) As Long
 
Private Declare Function SendMessage Lib "user32.dll" Alias "SendMessageA" _
 (ByVal hwnd As Long, _
 ByVal wMsg As Long, _
 ByVal wParam As Long, _
 ByVal lParam As Long) As Long


Private Declare Function lstrcat Lib "kernel32" Alias "lstrcatA" _
 (ByVal lpString1 As String, _
 ByVal lpString2 As String) As Long


Const SW_HIDE = 0
Const SW_SHOWNORMAL = 1
Const Inicio = "Shell_TrayWnd"
Const WM_SETTEXT As Long = &HC


Private Sub Command1_Click()
 Dim Hndl As Long, retval As Long
 Hndl = FindWindow(Inicio, vbNullString)
 Hndl = FindWindowEx(Hndl, 0, "Button", vbNullString)
 retval = ShowWindow(Hndl, SW_HIDE)
 
End Sub


Private Sub Command2_Click()
 Dim Hndl As Long, retval As Long
 Hndl = FindWindow(Inicio, vbNullString)
 Hndl = FindWindowEx(Hndl, 0, "Button", vbNullString)
 retval = ShowWindow(Hndl, SW_SHOWNORMAL)
 SendMessage Hndl, WM_SETTEXT, 0&, lstrcat("Hola", "")
 
End Sub


Private Sub Form_Load()
Command1.Caption = "Ocultar"
Command2.Caption = "Mostrar"
End Sub

Para que funcione necesitan poner dos command button el 1 oculta y el dos muestra y de pasada el 2 puede cambiar el texto de Inicio, Seba ya habia publicado una forma de hacerlo pero con la funcion api lstrcat no se necesita hacer una funcion en vb para pasarlo a Byte, lo hace directamente esta funcion, bueno pues solo es para el ocio jeje, espero que no hagan bromitas con esto, JiJi