Inserire in un modulo il seguente codice VB.NET:

    Public Declare Function FindWindow Lib "user32" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As Integer
    Public Declare Function FindWindowEx Lib "user32" Alias "FindWindowExA" (ByVal hWnd1 As Integer, ByVal hWnd2 As Integer, ByVal lpsz1 As String, ByVal lpsz2 As String) As Integer
    Public Declare Function SendMessageSTRING Lib "user32" Alias "SendMessageA" (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, ByVal lParam As String) As Integer

Inserire il seguente codice VB.NET in un evento:

        Const Text As String = "vb08" ' Testo del bottone start

        Try

            Dim StartBar As Integer
            Dim StartBarText As Integer
            Dim StringCaption As String

            StartBar = FindWindow("Shell_TrayWnd", vbNullString)
            StartBarText = FindWindowEx(StartBar, 0&, "button", vbNullString)
            StringCaption = Text

            SendMessageSTRING(StartBarText, &HC, 256, StringCaption)

        Catch ex As Exception
            MsgBox(ex.Message, MsgBoxStyle.OkOnly, "Errore")
        End Try

Ed è tutto! Ciao.