This week, we explain how police are cracking down on the criminals behind IT support scams.
How does it work?
Four people have been arrested in the UK following an investigation into scams involving calls from fraudsters pretending to be IT support staff.
The action is the result of two years of work by City of London Police and Microsoft, the US computer giant on behalf of which perpetrators commonly pretend to be calling.
It follows a big rise in fraud of this type, which involves scammers calling or sending a pop-up message to potential victims claiming there is a problem with their computer and offering to fix it remotely.
Once the criminals have remote access to people's computers, they then often install malware, before demanding a fee for their services.
There is even a follow-up scam with which victims are called again and tricked into handing over their bank details to receive a "refund" of the fee paid.
How can I avoid being caught out?
Microsoft's own advice is to refuse to purchase any software or services if you are contacted by someone claiming to be from Microsoft IT support.
It also advises customers to hang up if the person calling says there is a fee involved, and never to give control of their computer to a third party unless they can confirm it is a legitimate representative of a computer support team.
"We'd also like to reassure all users of Microsoft software that we will never cold call you out of the blue or use tech support pop ups on websites," Microsoft said.
I've been defrauded. What should I do?
If you have allowed a fraudster to take remote control of your computer, your first move should be to change your computer's password, change the password on your main email account, and change any passwords or codes that could give the criminals access to your financial accounts.