Prunellechamaret.com with the capital P actually IS the name of the domain folder for your account. Don't worry about that. Normally it's a lowercase P, but sometimes it happens.
The file wp-content/themes/matchbook2-child/includes/stop-ie6/stopie6.php doesn't exist.
The issue is matchbook2/functions.php is (for some reason) telling the theme that it should look in the CHILD and not the PARENT. I'm not a theme expert (I do plugins) so this took me a moment to detangle.
In the functions.php file, there's this:
include_once (STYLESHEETPATH . '/includes/stop-ie6/stopie6.php');
That's calling http://codex.wordpress.org/Function_Reference/get_stylesheet_directory which says "Retrieve stylesheet directory Path for the current theme/child theme." It shoudl be using the TEMPLATE path... And when I read the functions.php, I saw this:
// This path is set for use in a child theme. The code could be updated in a few places
// to TEMPLATEPATH if this was being used in a parent theme.
facepalm So the theme KNEW it was doing it wrong, and did it anyway.
To fix, change all references of STYLESHEETPATH to TEMPLATEPATH in functions.php for matchbox2, however I would go after that theme dev with a mallet and explain that if you know what to do and you don't do it, there you bloody well are, aren't you?