Some time back, I removed a nasty bit of malware holding a PC hostage. It claimed that child pornography was found on the PC by the FBI and that the user had to pay a $300 fine in 48 hours or risk arrest and PC hard drive deletion. Pay the fine, and everything goes back to normal. There was a nice little countdown timer and many convincing graphics and legalese. The scam wants you to use a "Green Dot MoneyPak". This is basically an electronic Western Union type service. It's untraceable and there's no way to get your money back. Luckily, the user was too wise to fall for the scam and sought help.
There are many versions of Western Union scams around, targeting many different groups. There are even some that target PC repair techs and businesses! The methods involve scare techniques such as this one, writing checks for amounts over what is expected and asking you to send back the rest, money laundering/moving schemes, etc. Nobody is safe. The simple rule is to never ever use money services such as Western Union or MoneyPak unless you have a solid concrete reason to do so. If someone truly wants to send you a prize, you won't need to send them money or credit card information first. Also, if the FBI or Police really want you for something, they will simply come and get you.