Hello Mary,
first of all I must say that I have turned the Theme settings -> Theme designer mode to Yes and I am using firebug tool in which I have turned off the caching so that all the changes are for sure immediatelly visible.
I've done the following steps:
1. renamed the folder of the theme
2. in config.ph changed the variable $THEME->name
3. changed the name of the language file in lang/en/ folder to theme_hartlauer
4. inside of the language file theme_hartlauer.php changed the variable $string['pluginname'] to 'Hartlauer' (I SUSPECT HERE SHOULD BE CHANGED THE PROBLEM FROM THE ATTACHMENT)
5. in renderers.php I have changed the name of the class to theme_hartlauer_core_renderer
6 in profileblock.php I have changed all the get_string's parameters to look into theme_hartaluer file.
I have searched throughout the whole project for the old name "aardvark" and it does not appear anywhere more !
RESULT: In the attachment You can see that in the Theme Selector the name of the theme is not changed and I have completely lost the profile block.
One other thing, how can I see these PHP_ERRORS I should be getting from the Developer:extra Moodle debug... ?