How do I stop Safari from occasionally downloading "mlingos9.html"?

Solution 1:

It's a problem with a specific web page — this one.

It specifies the content type application/octet-stream in the HTTP response headers, which is usually used for files meant to be downloaded — and that's what your web browser does. HTML web pages usually use text/html or similar HTTP headers, never application/octet-stream.

If you were browsing web sites with similar topics that might link to this web page, and you clicked a link, or the web page was included in another web page using a frame/iframe, that's the cause for the downloads.

Solution 2:

I'm the owner of that page. Strangely I have no problems seeing it myself. I am contacting Apple to ask them to fix the header sent by the server.

PS It turns out I was able to fix the problem by replacing that page with a local copy. Something about the one on the server was causing it (and only it) to be served as an application. I have no idea what could have caused that or how the copy of the file on the server got that way. If anyone else does, I'd be interested to hear it.