I’m not sure if at that point your installer was finished installing the snippets, or if it was in the middle of installing the snippets when it failed.
It might be interesting to make sure that PHP is reporting errors, then try again.
I’d open up /install/index.php, and add a line after
error_reporting(E_ALL & ~E_NOTICE);
so that you have
error_reporting(E_ALL & ~E_NOTICE);
ini_set('display_errors', true);
Then check source and firebug to see if you get any more clues.