Writing a Windows Service problem

Could someone please tell me where I'm going wrong... attempting to write a Windows service and have found a few examples but none of which have worked. The following code is the best so far but stops with the following message:-  (maximum points here for a quick answer)

"Service cannot be started. System.NullReferenceException: Object reference not set to an instance of an object."

It appears to be complaining about the Timer1.Enabled line

Here's the code:-

Public Class Service1
  Friend WithEvents Timer1 As System.Timers.Timer
  Protected Overrides Sub OnStart(ByVal args() As String)
    ' Add code here to start your service. This method should set things
    ' in motion so your service can do its work.
    Timer1.Enabled = True
    Timer1.Interval = 3000
  End Sub

  Protected Overrides Sub OnStop()
    ' Add code here to perform any tear-down necessary to stop your service.
    Dim timer1 As New Timer
    Timer1.Enabled = False
  End Sub

  Private Sub Timer1_Elapsed(ByVal sender As Object, ByVal e As System.Timers.ElapsedEventArgs) Handles Timer1.Elapsed
    Beep()
  End Sub
End Class

Thanks

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