Too bad the exact message was not revealed but you can type that into google.com and see if Grif's advice at http://forums.cnet.com/7726-6132_102-5098912.html?tag=posts;msg5099421 still applies.
As noted by Grif, you download using another computer.
When I try to log on to the internet from my laptop, a screen pops up that says it is some type of United States Security and I have to pay - even goes as far as turning on my video as if I am being watched. All I can do is turn my computer off. When I turn my computer back on, I can't activate my anti-malware support and I can't even do a reset to a previous date. I have tried going into safe mode, I can access the internet but downloading/running any virus protection did not work. The screen still comes up. What can I do?