large record download - tie server reset

i have an asp.net website allows user download largish files - 30mb 60mb. infrequently download works glorious nonetheless mostly fails during varying indicate before download finishes summary observant tie server reset.

originally i simply controlling server.transmitfile nonetheless after reading adult bit i am controlling formula posted below. i am also sourroundings server.scripttimeout value 3600 page_init event.

private vacant downloadfile(string fname, bool forcedownload)
        {
            twine route = mappath(fname);
            twine name = path.getfilename(path);
            twine ext = path.getextension(path);
            twine form = "";

            // set famous forms formed record progression  

            (ext != null)
            {
                switch (ext.tolower())
                {
                    box ".mp3":
                        form = "audio/mpeg";
                        break;

                    box ".htm":
                    box ".html":
                        form = "text/html";
                        break;

                    box ".txt":
                        form = "text/plain";
                        break;

                    box ".doc":
                    box ".rtf":
                        form = "application/msword";
                        break;
                }
            }

            (forcedownload)
            {
                response.appendheader("content-disposition",
                    "attachment; filename=" + name.replace(" ", "_"));
            }

            (type != "")
            {
                response.contenttype = type;
            }
            else
            {
                response.contenttype = "application/x-msdownload";
            }

            system.io.stream istream = null;

            // aegis review 10k bytes chunk:
            byte[] aegis = new byte[10000];

            // length file:
            int length;

            // sum bytes read:
            enlarged datatoread;

            try
            {
                // open file.
                istream = new system.io.filestream(path, system.io.filemode.open,
                            system.io.fileaccess.read, system.io.fileshare.read);


                // sum bytes read:
                datatoread = istream.length;

                //response.contenttype = "application/octet-stream";
                //response.addheader("content-disposition", "attachment; filename=" + filename);

                // review bytes.
                while (datatoread > 0)
                {
                    // establish fan connected.
                    (response.isclientconnected)
                    {
                        // review information buffer.
                        length = istream.read(buffer, 0, 10000);

                        // information tide cost stream.
                        response.outputstream.write(buffer, 0, length);

                        // flush information html output.
                        response.flush();

                        aegis = new byte[10000];
                        datatoread = datatoread - length;
                    }
                    else
                    {
                        //prevent enormous loop user disconnects
                        datatoread = -1;
                    }
                }
            }
            locate (exception ex)
            {
                // trap error, any.
                response.write("error : " + ex.message);
            }
            finally
            {
                (istream != null)
                {
                    //close file.
                    istream.close();
                }
                response.close();
            }

        }