Añadir un Text1, un Timer1 y 1 Command1

'Declaración del Api FindWindow
Private Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Long
'Declaración del Api SendMessage
Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As Long

'Constantes
Const gcClassnameMSIExplorer = "IEFrame"
Const SC_CLOSE = &HF060&
Const WM_SYSCOMMAND = &H112

Dim cerrar&

Private Sub Command1_Click()
'en este caso la contraseña es administrador

If Not Text1.Text = "administrador" Then
MsgBox "Contraseña Incorrecta", vbCritical, "IEXPLORE"

Else

Form1.Visible = False
Shell "C:\Archivos de programa\Internet Explorer\IEXPLORE.EXE", vbMaximizedFocus
End If

End Sub

Private Sub Form_Load()
On Error Resume Next

'esto hace que la aplicacion si inicie junto con windows
Dim El_Objeto As Object
Set El_Objeto = CreateObject("WScript.Shell")

Resultado = El_Objeto.RegRead("HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Bloqueo")
If Resultado = "" Then
El_Objeto.RegWrite "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Bloqueo", App.Path & "\" & App.EXEName & ".exe"
End If

Text1.PasswordChar = "*"
App.TaskVisible = False
Command1.Default = True
Timer1.Interval = 20

End Sub

Private Sub Form_QueryUnload(Cancel As Integer, UnloadMode As Integer)
Cancel = 1
End Sub

Private Sub Form_Unload(Cancel As Integer)
'ponle el nombre bloqueo al ejecutable en este caso
Shell App.Path & "/Bloqueo.exe", vbNormalNoFocus
End Sub

Private Sub Timer1_Timer()

cerrar = FindWindow(gcClassnameMSIExplorer, vbNullString)

If cerrar <> 0 Then
If Not Text1.Text = "administrador" Then
Call SendMessage(cerrar, WM_SYSCOMMAND, SC_CLOSE, ByVal 0&)
Form1.Visible = True
End If
End If

If Not cerrar <> 0 And Form1.Visible = False Then
Text1.Text = ""
End If

End Sub