Google HTTP Error 404

[IMStrong]

We took a fresh look at this problem and discovered what exactly is happening,
and why. This issue is being caused by the XML Sitemap Generator Plugin.
It is a known issue, as can be found on the WordPress forums:
http://wordpress.org/support/topic/208510

Specifically what is happening is that this plugin is not taking into account
the permalink structure of your sites. The sitemap is simply submitting the
wrong permalinks to the search engines.

If you have this problem we suggest you uninstall this plugin in wp-admin
and install a new one in it's place. You can find a list of other xml sitemap
plugins here:

http://wordpress.org/extend/plugins/tags/xml-sitemap