Well, it would help if you could give us some more information.
Security Centre says "your system is secure", which is a good sign; but you have viruses on your system? Okay, first, what told you that your PC was infected - a McAfee scan, or what? And, second, which viruses does your PC have on it? The experts can't help you until they know that, at least.
There is this pop up that always ask me to identify myself if i am a robort or human being which prevent me to browse. It is disgusting.
Yes indeed. The next time you see the pop-up could you take a screenshot of it and put the screenshot in your next message? Then we can examine it and decide what to do.