Stay one step ahead of the fraudsters with our series of articles giving you the lowdown on the scams they use to trick people out of their hard-earned cash - and how to avoid being taken in by them.
This week, we focus on so-called tech support scams purporting to come from legitimate software and internet service providers such as Microsoft.
How does it work?
Almost seven in 10 UK computer users have been targeted with tech support scams, according to the latest figures from Microsoft.
In the US, the percentage of internet users sent bogus messages of this kind jumps to 79%.
The computer giant's research also indicates that most tech scams start with emails, pop-ups or redirects, and that one in 10 of the Britons targeted have been fooled into responding to the messages.
Those who do respond are encouraged to either download software that will install malware designed to give criminals access to their personal data, or to pay for "tech support services" that often cost £100 or more.
How can I avoid being caught out?
It is best to ignore any unsolicited messages you receive claiming that malware has been detected, particularly if they also tell you to call a number "for immediate assistance".
Microsoft also advises users to never give anyone control of a computer or device before checking their identity. "Tech support should not be contacting you first – ever," it said.
I've been defrauded. What should I do?
It is vital to secure any bank or card accounts the fraudsters may have been able to get access to by infecting or taking control of your computer.
So call the relevant banks and card providers as soon as you realise you have been scammed.
Any payments made for bogus tech support are unlikely to be refunded, but you will also have a better chance of getting your money back if you contact your bank immediately.
Once you have done that, you should help to prevent more people being taken in by reporting the problem to Action Fraud (0300 123 2040).