Попробуйте использовать более длинную страницу 404.Это не шутка.Если страница 404 меньше 512b, если я правильно помню, IE войдет и покажет свое собственное сообщение об ошибке.
Добавление в некоторых комментариях будет делать.
Ссылка: http://www.reddit.com/r/web_design/comments/ee4zc/so_i_looked_at_plesks_404_page/
Просто для полноты:
<HTML>
<HEAD>
<TITLE>404 Not Found</TITLE>
</HEAD>
<BODY>
<H1>Not Found</H1>
The requested document was not found on this server.
<P>
<HR>
<ADDRESS>
Web Server at example.com
</ADDRESS>
</BODY>
</HTML>
<!--
- Unfortunately, Microsoft has added a clever new
- "feature" to Internet Explorer. If the text of
- an error's message is "too small", specifically
- less than 512 bytes, Internet Explorer returns
- its own error message. You can turn that off,
- but it's pretty tricky to find switch called
- "smart error messages". That means, of course,
- that short error messages are censored by default.
- IIS always returns error messages that are long
- enough to make Internet Explorer happy. The
- workaround is pretty simple: pad the error
- message with a big comment like this to push it
- over the five hundred and twelve bytes minimum.
- Of course, that's exactly what you're reading
- right now.
-->