Moneypak FBI wants $200 Help

Hello,

I got the moneypak FBI $200 scam on my main house PC today.  Its a HP with windows 7 home premium and I am using Norton Internet Security.  Computer seems to work fine when not connected to internet.  The only thing I did was run a virus scan using Norton Internet Security and it came up with nothing.  I have not tried anything else.  Can you help?