The Admin Site Archive tool produces unparseable XML for these tools / archive types:

attachment.xml
content.xml
site.xml
syllabus.xml
user.xml
wiki.xml

This can be seen by viewing the resulting files in Firefox, which produces the error:

XML Parsing Error: prefix not bound to a namespace
Location: file:///c:/tmp/1a16b939-aced-4137-0027-6c5276812f93-archive/attachment.xml
Line Number 4, Column 5: <sakai:content>
----^

Tools which produce valid (parseable) XML are structured like this (e.g. Announcements):

<archive date="20061030122049102" server="mocha" source="1a16b939-aced-4137-0027-6c5276812f93" system="Sakai 1.0">
<org.sakaiproject.announcement.api.AnnouncementService>
...
</org.sakaiproject.announcement.api.AnnouncementService>
</archive>

whereas the invalid ones are structured like:

<archive date="20061030122049102" server="mocha" source="1a16b939-aced-4137-0027-6c5276812f93" system="Sakai 1.0">
<sakai:rwiki>
...
</sakai:rwiki>
</archive>

"sakai" is interpreted as the prefix for a namespace which is not defined.

These XML files therefore either need xmlns declarations to define the namespace correctly, or need to avoid the use of namespace prefixes.