Police have warned internet users of the latest cyber scam called Cryptowall.
The malicious software, or malware, infects a computer and makes in inoperable until a user pays a 'ransom fee'.
It spreads by infecting website links which are sent via email or accessed through advertisements on trusted websites.
By clicking on the advert and going to a third-party website users may be asked to download a document which is infected.
The website can also be corrupted to run a scan on the user's machine and take advantage of any security flaws before then being able to install the malware.
In some cases, users might think they are installing a video plugin or an update only to discover their computer has been taken over by the software.
Once Cryptowall has taken over it renders the computer unusable unless a fee is paid to the cyber criminals.
PC Chris Dover said that although there have not been any cases reported to Nottinghamshire Police people needed to be aware of the scam to avoid falling victim to it.
He said: "Many of us use the internet as part of our daily lives, for banking, shopping, socialising and entertainment.
"We have to be aware of the potential risks to our computers to avoid cyber criminals winning and people paying hefty fees to have their computers repaired.
"Never click an embedded link in an email from someone you don't know or an untrusted source.
"Keep your computer up to date with antivirus software and delete programs you no longer need or use.
"Additionally, be more cautious about the emails you open and consider running an advert blocker in your browser.
"Finally make backups of your important data and keep them separate from your computer.
"That way, if the worst happens, you should be able to restore your valuable data."
Have you ever been affected by a cyber scam? Get in touch: newsdesk@nottinghampost.com