Ошибка открытия файла, так как он занят другим процессом

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        IO.File.Open("C:\Secret firmi\files\Instruction.txt", IO.FileMode.Open)
    End Sub

FileClose()

Process.Start("имя файла")

Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        IO.File.Open("C:\secret firmi\files\Instruction.txt", IO.FileMode.Open)
    End Sub

Process.Start("notepad.exe", "C:\11.txt")

Public Class Form1
 
    Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        TextBox1.Multiline = True
        TextBox1.Dock = DockStyle.Fill
        TextBox1.ReadOnly = True
        TextBox1.Text = _
            System.IO.File.ReadAllText("C:\11.txt")
    End Sub
 
End Class

Public Class Form1
 
    Private Sub Form1_Load(sender As Object, e As System.EventArgs) Handles Me.Load
        Me.MaximizeBox = False
        TextBox1.Multiline = True
        TextBox1.ReadOnly = True
        TextBox1.ScrollBars = ScrollBars.Vertical
        TextBox1.Height = Me.Height - 100
        TextBox1.Dock = Me.Width
    End Sub
 
    Private Sub Button1_Click(sender As Object, e As System.EventArgs) Handles Button1.Click
        Dim Dialog As New OpenFileDialog With {.FileName = Nothing, .Filter = "txt files(*.txt)|*.txt"}
        If Dialog.ShowDialog = DialogResult.OK Then
            TextBox1.Text = System.IO.File.ReadAllText(Dialog.FileName)
        End If
    End Sub
End Class