Need help removing antivirus system pro

all of a sudden today I have this antivirus system pro and it continues to pop up on my screen as well as my pop up blocker is no longer functioning because porn is popping up all over the place. Please help!!!!

wow...really????? That was all it took...gosh this was easy....since I have been down with the swine flu...maybe things are looking up finally!!!! Thank you so much!!!!