Last Friday, scammers struck several Champaign County computers, probably from California. They froze the computer screen with an ad that covers all icons, so one cannot “shut down.” They offer only a phone number to call, and will tell the victim that a major software company has authorized them to deal with hackers who have allegedly attacked earlier. They will unfreeze the screen for a credit-card payment of around $300, and offer to be the new security service to protect future hacking.
Computer techs advise the victim to do nothing before they can deal with the freeze. That may mean unplugging the CPU tower and taking it to a reputable tech service. Dealing with the credit-card information requires calling the company (VISA, etc.) and detailing the scam. Getting the money back requires first getting the computer back to normal operating state so that no reprisal can be carried out.
The scammers may have collected other credit-card details and banking information, so all those numbers should be changed quickly. Of course, once having struck your computer, they can strike again, but they usually target a community and move on. No protection service (Norton, McAfee, etc.) is 100 percent fool-proof. A good site to visit for their methods is https://blog.malwarebytes.com (Help & Resource page). The attack should be reported to the software company you use and the State Attorney General.