Welcome you here. Don't worry about the infection about this FBI lockup virus you've mentioned here. It is totally a trick for money extorting and this virus is classified as ransomware which invades the computer to ask for a ransome to unlock the compromised pc, generally. In most cases, it is so nasty to even block the pc from running in safe mode. Therefore, it requires some special removal tools to get rid of that and fix the issue. For you convenience, we've written a detailed guide to remove this FBI pc lock infection in this post: http://forums.anvisoft.com/viewtopic-45-1178-0.html
Read more there and if any further question in the process, please feel free to get in touch. Good luck.