There is currently a "Security" email going around informing people using PayPal that their transactions have been placed in a "Restricted" state, as one or more credit cards have not been confirmed.
Do not confirm your credit card details or give any information on the site the norice links to. It is a fraud.
Forward any emails pertaining to be from PayPal to email@example.com.
They will investigate and reply to you whether the email is genuine, a virus or an attempted fraud.
Please note that the headers on the email appear to come from paypal.com, and a large number of people are being taken in by this.