This contact form contains CAPTCHA fields, but the temporary folder for the files (/wp-content/uploads) does not exist or is not writable. You can create the folder or change its permission manually.
The uploads folder DOES exist, as does wpcf7_images and wpcf7_uploads. They're all CHMODed to fullest permissions possible. My php.info file says my GD and FreeType are enabled. But that's the message I get when I try to add Really Simple Captcha to Contact Form 7, even though I've deleted and re-installed them twice.
The only potential problems I can think of are that the site is XHTML Strict and in a sub-directory--though I've added a php.ini file and a handler command to the sub-directory's .htaccess file. Under Settings/Miscellaneous on the WP dashboard, I have the uploads URL as http://www.maindirectory.com/subdirectory/wp-contents/uploads since wp-content/uploads didn't do the trick. Which puts me completely out of ideas!