How to Associate File Type or File Extension to Default Program in Windows Vista
Windows Vista might not assign HTM or HTML file extension to Microsoft Internet Explorer (IE), but Vista will launch Internet Explorer when we click on the HTML pages.
If the computer doesn't assign HTM file extension to the Internet Explorer and the application want to open a HTML page by file extension, then the application cannot find the associated default program and cannot open that HTML page.
Setup HTM file extension associating with Internet Explorer
Setup HTM file extension associating with Internet Explorer for Windows XP computer
Fortune Angel Chinese Astrology and Chinese Farmer Calendar Installation Help for Windows Vista