Cheatsheet Link Not Working Correctly

When I click on the W3C cheatsheet link on your home page, i.e., http://www.w3.org/2009/cheatsheet/, in IE 9, it wants me to download and open the page instead of displaying it. What do I need to do to fix this problem? BTW, it was working fine in IE yesterday, albeit on a different computer.
 
Thanks,
 
David W. M. Stendel
Associate Professor
Architecture, Engineering & Technology
Business, IT & Public Services