Four people have been arrested in the UK following an investigation into scams involving calls from fraudsters pretending to be IT support staff.
It follows two years of work by City of London Police and Microsoft, who teamed up to tackle the problem.
The perpetrators commonly pretend to be phoning on behalf of the US company.
The inquiry indicated that many of the calls originated in India but two men and two women in England have been accused of involvement.
They include a 29-year-old man and a 31-year-old woman from Woking in Surrey, who were arrested on suspicion of fraud. Both have been bailed.
A 37-year-old man and a 31-year-old woman were arrested in South Shields, Tyneside, on suspicion of fraud. Both were released pending further inquiries.
There were 34,504 computer software service fraud reports made to the UK's national fraud and cyber-reporting centre, Action Fraud, over the past financial year.
The scammers usually declare that they have detected a fault with their target's PC and fool victims into giving them remote access to it. They then often install images that appear to show the computer is infected or install malware themselves.
Finally, they demand a fee to fix the issue or otherwise convince the victim to share their bank account details.
Action Fraud says the average age of victims is 62 and they typically pay out £600.
"These arrests are just the beginning of our work, making the best use of specialist skills and expertise from Microsoft, local police forces and international partners to tackle a crime that often targets the most vulnerable in our society," said Commander Dave Clark from City of London Police.