I didn't pay attention to some program I installed and it also installed a free thing called "Norton Security Scan". So I uninstalled it from add/remove programs, it appeared to uninstall normally, logos and folders removed and no longer appeared in the program list. But every time I reboot it magically reappears on the PC, the icon appears on the desktop and it reappears in add/remove programs. It's like a ****ing virus. How do I get rid of it?