[Help] MD5 Updater

  Public Sub CheckSumAndRun(ByVal filename As String)
        Try
            f = New System.IO.FileStream(filename, System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.Read, 8192)
        Catch ex As Exception
            MsgBox(ex.Message)
            Exit Sub
        End Try
        md5 = New System.Security.Cryptography.MD5CryptoServiceProvider
        md5.ComputeHash(f)
        Dim hash As Byte() = md5.Hash
        Dim buff As System.Text.StringBuilder = New System.Text.StringBuilder
        Dim hashByte As Byte
        For Each hashByte In hash
            buff.Append(String.Format("{0:X2}", hashByte))
        Next
        f.Close()
        If buff.ToString = main_md5 Then
            p = Diagnostics.Process.Start(main_name, MainStartParam)
            Me.Close()
        Else
            If My.Computer.FileSystem.FileExists(currdir & main_name) = True Then
                My.Computer.FileSystem.DeleteFile(currdir & main_name, FileIO.UIOption.OnlyErrorDialogs, FileIO.RecycleOption.DeletePermanently)
            End If
            wrong_main = True
            BackgroundWorker1.RunWorkerAsync()
        End If
    End Sub