So, further investigation shows that the problem is that Internet Explorer does not support xhtml.
Yes, xhtml, a standard web format defined in 1999, is still not supported by Microsoft's latest and greatest browser. Make your own judgements about Microsoft. I made mine years ago.
I've converted the files into normal html now, and have validated all of them. They should work on ANY web browser developed in this century.
Results are available at http://www.ameri.me/fgp/2009/