Unfortunately, we've stopped supporting Windows XP and Vista. These operating systems are no longer receiving security patches from Microsoft and we can no longer consider them safe for general use.
Going forward, we would recommend using OpenVPN rather than our application. You can find our Windows OpenVPN setup guide here: https://piavpn.com/hc/115000244471-PIA-Setups#openvpn
We're very sorry for the inconvenience with this, and hope we can continue helping you protect your traffic!