Online users in Glasgow have been targeted by the scam, in which the fraudsters claim to be working for the police force.
A pop-up window appears on the person's computer, telling them the machine has been locked by officers.
The bogus message tells the user he or she had looked at "violent content" – even when this is not the case.
The message has the police logo in an attempt to add authenticity to the scam.
Those targeted are then told to visit a website, called ecash, where they are asked pay £100 to get their computer unlocked.
At least four people in Glasgow have been targeted, with one paying out the £100.
One person in Springburn has fallen for the scam, while one in Robroyston and two others in Barmulloch have been targeted in the last fortnight.
There have also been reports of the pop-up appearing on other users' screens with the logo of the Metropolitan Police.
One Glasgow resident who was targeted said: "I was on my computer, using the internet, when the screen suddenly froze.
"Next thing a message popped up on the screen, saying it was from Strathclyde Police and that officers had frozen my computer because of what I had been looking at.
"It told me to go to a website and pay £100 to unfreeze the screen.
"The pop-up had the Strathclyde Police logo on it, so it looked authentic. I can see why people have fallen for it.
"I panicked when I saw it and didn't know what to do.
"Then I noticed some of the spelling in the message was wrong and that tipped me off it was a scam. I switched my computer off and back on again, and the screen was back to normal, with the message having disappeared."
Detective Constable Adam Mitchell, of Strathclyde Police Economic Crime Unit, said: "The force is investigating a number of complaints involving an internet scam.
"We would like to assure the public this scam has nothing to do with Strathclyde Police and that the force never asks the public for money.
"We would urge people not to follow the instructions on screen, do not call the number and do not send money.
"Anyone who has received this scam pop-up on their computer should contact their local police office as soon as possible."
Last month, the Evening Times told how internet users were warned about a similar computer scam, where a message claiming to be from police asked people to pay a £100 fine.
Strathclyde Police said a pop-up window appears on computer screens telling users their machine had been locked.
The message claims they have been viewing adult content online when this is not the case.
It then asks users to pay a £100 fine over the phone.