It seriously worries me that these scams keep reappearing. It means that someone, somewhere is making it profitable to continue making them.
These people broke into your computers. Don't pay them. Nobody serves legal notice by instant messaging or little pop-up windows (unless it's from some court that's exhausted EVERY possible way of contacting you, including going via your ISP, and then - does that SOUND like a lawyer to you?). They've popped up a window on your screen against your will after gaining entry to a private PC - just how "helpful" do you think they are trying to be by inciting you to "cover up" your torrents and asking money to do so?
I don't find the existence of viruses surprising - never have, even since the DOS days. Some people just find it a good prank to delete your hard drive or email everyone you know anyway, and some just wrote programs to do just that. I do find their *continued* existence quite annoying, though. Just who exactly is making it profitable to take the risk of creating something like that that may be traced back to you (even if by accident - say, your code takes out a hospital or something equally important, and someone comes looking for you)?
And, for years, viruses have tried to kill programs that might fix them. Several of them kill regedit when detected, for example, because it's quite good at cleaning out Run entries and file associations, not to mention the thousands that kill things like debuggers, antivirus, etc. There's nothing "new" here. People are stupid. That's not new.
So much for modern Windows letting you "keep control" of things like this. Seriously, why does no modern OS STOP programs doing things like killing other, completely unrelated, processes?