http://i.imgur.com/gGDexLF.png < Screenshot of the popup
I accidentally mystyped www.roblox.com (I typed it as www.riblox.com) and it sent me to the fake popup.
The number provided was 1-888-361-4001. Call them and piss them off.
UPDATE: Link to the popup: hxxp://wordizknl1.xyz/windows/error01
P.S. This popup will not lock your browser, however it will make your cursor dissapear if you move it inside the website.