Yesterday google removed our index page from the results.
Today they also removed language subdomains (fr.domain.com)..
Index page, subdomains are not indexed anymore.
No messages in GWT. No malware.
Backlink diversification was started in May.
Never penguilized or pandalized.
Last week had the record of all times of daily UV.
Other pages still indexed and driving traffic, left around 40% of total.
Never used any black SEO tool. 95% of backlinks are related; sidebar, footer links
No changes made of index page for couple months.