Response.Clear();
                string pdfPath = Config.GetSetting("VirtualDirectoryPDFs").ToString() + "\\";

                if (Request.Params["filename"] != null)
                {
                    string file = pdfPath + Request.Params["filename"].ToString();

                    if (File.Exists(file))
                    {
                        Response.ContentType = "application/pdf";
                        FileStream fs = new FileStream(file, FileMode.Open, FileAccess.Read, FileShare.Read);
                        long fileSize = fs.Length;
                        byte[] bytes = new byte[fileSize];
                        fs.Read(bytes, 0, (int)fileSize);
                        fs.Close();
                        Response.OutputStream.Write(bytes, 0, (int)fileSize);

                    }                     
                }      
           
                Response.End();

THX