Cforms and Lytebox not working anymore…

Hello !

I have got a few problems with my website http://www.alexandragiroux.net

It used to work but now I have got some troubles, especially with two plugins : Cforms (people cannot send their messages – page “contact”) and Lytebox (the image opens in a new page, like in the page “medias”).

I have tried to deactivate all the plugins but it’s not working either…
I was wondering if it can be a problem related to the folder authorisation…

Or maybe it is related to mysql and I should delete some tables?

wpau_active_plugins_info
wpau_upgrade_log
wp_ak_404_log
wp_blc_linkdata
wp_blc_postdata
wp_comments
wp_links
wp_options
wp_page2cat
wp_posts
wp_py_jobs
wp_py_jobs_data
wp_seo_title_tag_category
wp_seo_title_tag_tag
wp_seo_title_tag_url
wp_terms
wp_term_relationships
wp_term_taxonomy
wp_usermeta
wp_users
wp_wpo_campaign
wp_wpo_campaign_category
wp_wpo_campaign_post
wp_wpo_campaign_word
wp_wpo_log
26 table(s) Sum 2,232 MyISAM latin1_swedish_ci 1.5 MiB 0 B

My plugins:
cforms
FD Feedburner Plugin
Google XML Sitemaps
MaxBlogPress Favicon
One Click Plugin Updater
Optimize DB
Random Redirect
ShareThis
Simple Archive Generator
Simple Tags
Wordpress Automatic Upgrade
WordPress Database Backup
WP-phpMyAdmin
WP-Lytebox

I have tried to upload again wp-admin and wp-includes but nothing changes… Anyone has an idea about what is wrong? I think it should be related to a plugin that I have installed and then deleted but I am not sure which one…

In advance, thank you very much for your help!