It all began when hackers took control of more than 570,000 infected computers around the world. Last year, the FBI set brought in a private company to install two clean internet servers to take over for the malicious servers, so people would not suddenly lose internet access, but that temporary system will be shut down at 4.01am UK time on Monday.
To check whether a computer is infected, users can visit a website run by the group brought in by the FBI: http://www.dcwg.org.)