Option Explicit

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

Private Const SW_HIDE As Long = 0
Private Const SW_NORMAL As Long = 1

Private Sub OcultarVentana(Handle As Long)
Call ShowWindow(Handle, SW_HIDE)
End Sub

Private Sub MostrarVentana(Handle As Long)
Call ShowWindow(Handle, SW_NORMAL)
End Sub

Private Sub Form_Load()
OcultarVentana Me.hwnd
End Sub

HWND FindWindow(

    LPCTSTR lpClassName,	// pointer to class name
    LPCTSTR lpWindowName 	// pointer to window name
   );	

BOOL ShowWindow(

    HWND hWnd,	// handle of window
    int nCmdShow 	// show state of window
   );

call ShowWindow(FindWindow(0,"Nombre_ventana"), SW_HIDE)