See the post link below for Microsoft’s advice on how to deal with this type of threat
Microsoft Corp. today released findings of a survey* into an emerging form of Internet scam that targets English-language markets and costs victims on average $875 (U.S.).
The scam works by criminals posing as computer security engineers and calling people at home to tell them they are at risk of a computer security threat. The scammers tell their victims they are providing free security checks and add authenticity by claiming to represent legitimate companies and using telephone directories to refer to their victims by name.
Once they have tricked their victims into believing they have a problem and that the caller can help, the scammers are believed to run through a range of deception techniques designed to steal money.