What is XP Antivirus 2012? How do I remove it?

Hi ladies and gents, today I was using my computer, like any other day. Then suddenly, all my browsers closed and this XP Anti-virus 2012 popped up and said I had 30 infections. It said I had to pay for the program to get rid of them, I didn't pay since i already had an anti virus installed... So after running a scan, I was surprised to see that I had infections on my computer, so I cleaned out the infections. After, the XP Antivirus 2012 still wouldn't go away... I thought I had to reset my computer... So I did. When I logged back on, it still popped up and said i had 30 infections still... So I repeated what I did before.. (scan, clean, reset) and the XP Antivirus 2012 STILL won't go away... It won't let me access my internet, it constantly brings pop ups saying that I have infections, constantly tells me that I have to purchase this program. I scanned my computer numerous times already! And this program STILL won't go away... What is this program? How can I remove it? Please help me :) and thanks for your time reading this. I appreciate all the help. :)