DocBook fails the IE test

All,

Just noticed that IE 6.0 fails, when valididating DocBook 4.3,
4.4 and 4.5b1. With 4.2, there is no problem. An error happens, when using
IE's "display XML" mode.

The following documents works with DocBook XML 4.2, but not the following
versions

<!DOCTYPE para PUBLIC "docbook DTD" "docbkx42/docbookx.dtd">
<para>What a strange parser, Microsoft seems to have created</para>

Regards,

Jens