Your computer has likely been infected by a virus named Sirefef.gen!C. Sirefef.gen!C is a computer virus that intercepts secure web connections and can steal passwords and other sensitive data.
Chrome recognizes this virus, but it affects all software on the computer. Other browsers and software may continue to work, but they are also affected and insecure.
Microsoft Security Essentials can reportedly remove this virus. When the virus is removed, the warnings in Chrome will stop. Learn more about Win32/Sirefef.gen!C virus in Microsoft's Malware Protection Center