Программно закрыть окно MessageBox

    Private Declare Function MessageBoxTimeOut Lib "user32" Alias "MessageBoxTimeoutA" (ByVal hWnd As Integer, ByVal lpText As String, ByVal lpCaption As String, _
                      ByVal uType As MsgBoxStyle, ByVal wLanguageId As Integer, ByVal dwMilliseconds As Integer) As Integer
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        MessageBoxTimeOut(Me.Handle, "Пример Messagebox'а с таймаутом", "Автоматически закроется через 3 секунды", MsgBoxStyle.Information, 0&, 3000)
    End Sub

AxMsTscAxNotSafeForScripting1.Server = txtIP.Text
AxMsTscAxNotSafeForScripting1.UserName = "test"
AxMsTscAxNotSafeForScripting1.Connect()

    <DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
Private Shared Function FindWindow( _
     ByVal lpClassName As String, _
     ByVal lpWindowName As String) As IntPtr
    End Function
    Private Const WM_CLOSE As Integer = CInt(&H10)
    <DllImport("user32.dll", SetLastError:=True, CharSet:=CharSet.Auto)> _
Private Shared Function SendMessage(ByVal hWnd As IntPtr, ByVal Msg As UInteger, ByVal wParam As IntPtr, ByVal lParam As IntPtr) As IntPtr
    End Function
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim hWnd As IntPtr = FindWindow("#32770", "Блокнот")
        If hWnd <> 0 Then
            SendMessage(hWnd, WM_CLOSE, 0, 0)
        End If
    End Sub

 Dim hWnd As IntPtr = FindWindow("#32770", "Безымянный — Блокнот")
        If hWnd <> 0 Then
            SendMessage(hWnd, WM_CLOSE, 0, 0)
        End If

 Dim hWnd As IntPtr = FindWindow("Notepad", "Новый текстовый документ.txt — Блокнот")
        If hWnd <> IntPtr.Zero Then
            SendMessage(hWnd, WM_CLOSE, 0, 0)
        End If