Many of us have received a phone call from them - so-called Microsoft employees who tell you something is wrong with your computer and they are here to help you.
The best thing to do is hang up and forget about them.
The phone scam is on a global scale and now joint action between three international regulators has resulted in US court orders to close down and freeze the funds of these Microsoft imposters offering to fix PC viruses.
The Australian Communications and Media Authority, (ACMA), the US Federal Trade Commission (FTC) and the Canadian Radio-television and Telecommunications Commission (CRTC) came together to share key intelligence about the operations of the scammers.
ACMA first became aware of the scam in 2009, after its Do Not Call register was swamped with complaints.
The scam generated nearly 10,000 complaints over the past two years, and at its peak was about 50 per cent of all reports.
"The message for scammers is they cannot use the global and borderless world of communications to avoid laws that protect Australians against scams," said ACMA chairman Chris Chapman.
"With new scams appearing more frequently, our citizens need to be vigilant and not respond to insidious trickery."
He said ACMA was committed to working with fellow regulators to stop scams, spam and unwanted telemarketing.
Mr Chapman said the best way to thwart scammers was to simply hang up and never give an unsolicited caller access to their computer or their credit card details.
He said Australia was one of the first targets of the scam, which went global.
ACMA has been tracking the Microsoft imposter scammers for three years working with the Australian Competition and Consumer Commission and the FTC.