I have this annoying PC LIVe Guard program that has suddenly appeared on my computer! How do i get rid of it?

It's driving me NUTSO!!!!! Somehow it had gotten onto my computer and I cannot get it off! I can't do anything on the internet without it popping up with this horrible loud noise, and interuppting all my programs. I can't figure out how to get it off my computer. It keeps saying I need to pay stinkin 50 bucks to install it! Please help! Anyone know How I can get rid of it???