I've looked into this and cannot identify the cause. Windows handles HTML files specially anyway (e.g. if you have Microsoft Word installed, if a *.html file contains certain <meta> elements then the file will have the Word HTML icon instead of the standard HTML file icon). For this, and other reasons, I strongly suggest running xpize after you've installed Windows, rather than patching a CD image. If I ever do release a new version, I'll remove the I386/CD-image patching feature because it doesn't work as-intended.