IE6 can't download file

Question

I've written a Web server that serves various kinds of content.

When sending back a JSON or CSV file, IE6 is unable to save the file. Firefox 3.6 and IE8 save those files just fine.

The server uses the text/json Content-type for JSON and text/csv for CSV files. I've tried changing the Content-type to text/plain -- no difference.

IE6's behavior, in more detail: it prompts the user to save the file; the dialog box shows the correct filename and number of bytes. After clicking OK, the download hangs.

I've instrumented the server, and from the server's perspective, the entire file is sent back.

Maybe IE6 needs some cue from the server to know that the response has finished. I'm calling shutdown() when the server is done sending a file.