This one is bad, comes in pop ups on sites you may visit to download music etc, holds your PC for ransom, locks it up bigtime.
Here is a link that might be useful: FBI Ransom Virus
its been around for a while actually
Are you saying this is happening on mainstream, reputable sites?
Well you know what the experts say...
Frequent hand washing reduces chances of viruses & when you cant wash to rub your hands together like you were washing them to squish and rip apart those tiny little buggers.
Yes, you can get it from almost anywhere, doesnt have to be any particular site. I have removed it a few months ago from a computer that was brought to me. It is actually fairly easy to remove completely, but it is a bit time consuming. Just make sure you do not pay any money, like they ask. It wont get your computer back working, even if you do.