If you are running this locally with Chrome, please be aware that Chrome will not allow you to open local file URLs.  To get around this, you should use a local URL via localhost.

Eg: 

http://127.0.0.1/~oscar/Snakes/snakes.html

http://localhost/~oscar/Snakes/snakes.html

Be sure that localhost or 127.0.0.1 is not routed to a proxy server!

Oscar Nierstrasz
2012-04-23