How can i get ride of this program on my computer?

[Jack]

I have a windows xp and i accidentally downloaded Personal anti virus and now i cant get on facebook. My computer has an anti virus program on it all ready. please help.

[Hawaiian Eskimo]

Start your PC in safe mode with networking by hitting F8 while your computer is booting (start tapping it before Windows starts to load to get the boot options menu). Then go and download Malwarebytes (http://www.malwarebytes.org/, you might have to download it on another computer and put it on a flashdrive if the site was blocked by the malware, and rename the file to prevent that from being blocked as well), and install, update, and run it. Then remove what it finds and restart your computer.