Problem with Upload Error handling

When the user uploads the file greater than the length specified in
web.config/machine.config, I always see the DNS Error page eventhough I have
handled the error Page_Error Event.

And this is my code in Page_Error event,

   Private Sub Page_Error(ByVal sender As Object, ByVal e As
System.EventArgs) Handles MyBase.Error

       Dim ex As Exception = Server.GetLastError.GetBaseException

       If TypeOf (ex) Is HttpException Then

           Dim oEx As HttpException = CType(ex, HttpException)
           If oEx.ErrorCode = -2147467259 Then
               Dim ErrorLabel As New Label
               ErrorLabel.ForeColor = System.Drawing.Color.Red
               ErrorLabel.Text = "La dimensione del file supera la
dimensione massima consentita di 4MB"
               Dim oCell As New HtmlTableCell
               oCell.Controls.Add(ErrorLabel)
               trUpload.Cells.Add(oCell)
               Server.ClearError()
               Response.ClearHeaders()
               Response.Status = "200 OK"
               Response.End()
           Else
               Throw New ApplicationException(oEx.Message, oEx)
           End If
       Else
           Throw New ApplicationException(ex.Message, ex)
       End If

   End Sub

I tried to set later just to get rid of DNS Error

Response.Status = "200 OK"
Response.End()

But in vain.

Can anyone shed some light on this? Why so Response.Status does not work?

TIA,
Holy