ASP.NET

try
{
  if (File.Exists(fullFilePath))
  {
    using (StreamReader _streamReader = new StreamReader(fullFilePath))
    {
      using (Stream _stream = _streamReader.BaseStream)
      {
        Response.Clear();
        Response.AddHeader("content-disposition", 
          String.Format("attachment;filename={0}", Path.GetFileNameWithoutExtension(fullFilePath)));
        Response.Charset = "";
        Response.Cache.SetCacheability(HttpCacheability.Public);
        Response.ContentType = DataAccess.GetMIMEType(Path.GetExtension(fullFilePath));
        Response.BufferOutput = false;

        byte[] _buffer = new byte[1024];
        int _counter = _stream.Read(_buffer, 0, 1024);
        while (_counter > 0)
        {
          Response.OutputStream.Write(_buffer, 0, 1024);
          _counter = _stream.Read(_buffer, 0, 1024);
        }

        Response.End();

      }
    }
  }
}
catch (Exception)
{ }