En español  |  Cybercrooks have a new way to steal your money: a virus that generates a bogus FBI message accusing you of watching child pornography or engaging in some other illegal online activity — then instantly freezes your computer.

It's a scam, of course. The goal is to extort a "fine" of $100 to $200, purportedly to be paid to the U.S. Department of Justice. Send it as a MoneyPak order, you're told, and your computer will be unlocked.

If you pay, you may receive a 10-digit password that allows you to unfreeze your computer. Or you may get nothing, or demands for more payoffs to the people who are holding your computer hostage. That's why the virus is called "ransomware."

Sometimes it's possible to unfreeze your machine yourself by such steps as turning it off and restarting it in "safe mode." But the FBI's Internet Crime Complaint Center (IC3) warns that this doesn't neutralize the threat, because this virus is very versatile.

It may continue to capture personal information such as your user names, passwords and credit card numbers, and send them to the scammers. IC3 reports getting dozens of complaints a day about the ransomware scam.

Known as Reveton, the virus is a variant of the Citadel malware that cybercrooks use to hijack online banking accounts. If you suspect you've been hit, the FBI advises you to hire a professional to check your computer. You should also file a complaint on the IC3 website.

Like other malware, Reveton is usually installed on your computer when you open a malicious attachment, click on a link in an email or instant message, or visit scammer websites that promise such things as enticing videos or free prizes.

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So to prevent infection, follow these steps:

• Do the obvious: Don't open spam or emails from people you don't know. Don't visit sketchy websites.

• Make sure your operating system's automatic updating feature is turned on so you'll get the latest security protection. Windows users should download the free Microsoft Security Essentials. Macs are less vulnerable to ransomware, but Apple encourages Mac users with ransomware concerns to contact its support team.

• Keep your firewall turned on. This software blocks outside parties from tampering with the programs installed on your machine.

• If you use Adobe's Acrobat PDF reader, make sure you update it to the latest version or switch to another PDF reader.

• Consider using security firm F-Secure Labs' free check-up tool to detect ransomware and other threats.

Sid Kirchheimer is the author of Scam-Proof Your Life, published by AARP Books/Sterling.