Impedir ejecutar más de una vez la misma aplicación

Imports System.IO 
Imports System.Management 
Imports System.IO.Path

   Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load 
        '============================ 
        '===    Las Variables 
        '============================ 
        Dim Process As New ManagementObjectSearcher("SELECT * FROM Win32_Process") 'Leemos los procesos
        Dim info As ManagementObject 
        Dim stock As String 
        Dim vrs As Integer 
 
        '=== Recuperación de información del exe 
        Dim MyNameApp As New FileInfo(Application.ExecutablePath)   ' dónde está el programa
        Dim SingApp As FileVersionInfo = FileVersionInfo.GetVersionInfo(MyNameApp.Name) 
 
        For Each info In Process.Get 
            stock = info("Caption").ToString() 
            If stock = SingApp.OriginalFilename.ToString() Then 
                vrs = vrs + 1 
                If vrs > 1 Then 
                    MessageBox.Show("La aplicación '" & MyNameApp.Name & "' ya está ejecutándose", MsgBoxStyle.Critical) 
                    End 
                End If 
            End If 
        Next 
    End Sub

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click 
        Process.Start(Application.ExecutablePath) 
    End Sub