Have you checked if your sitemaps duplicate eg "index.html should not be included"
<url>
<loc>http://www.expletia.co.uk/</loc>
<lastmod>2007-01-01</lastmod>
<changefreq>weekly</changefreq>
<priority>1.0</priority>
</url>
<url>
<loc>http://www.expletia.co.uk/index.html</loc>
<lastmod>2007-01-01</lastmod>
<changefreq>weekly</changefreq>
<priority>1.0</priority>
</url>
Contrary to most MSN does read sitemaps but you have to wait for it to be found, to speed it up you can include temp links on your main pages
MSN States:
http://help.live.com/help.aspx?project=wl_webmasters
left menu, open
How can I make sure my website is correctly indexed?
open
Content guidelines for your website
Quote" "Add a site map. A site map helps MSNBot to find all of your pages"
To alleviate your prob i would included Sitemaps:
ror.xml "independant"
sitemap.xml "Google"
sitemap.txt "Yahoo"
sitemap.html "max 100 links, otherwise spamming"