My computer is infected with a virus, should I install Principal AntiVirus now ?
Although Principal AntiVirus will be able to stop the virus running in your computer, irreversible damage may have already happened. The safest approach is to reinstall Windows by booting from an installation CD and selecting to format the installation partition during setup. Best practice is Principal AntiVirus by installing and enabling it before running any dangerous program. Installing and running Principal AntiVirus on an already infected machine is tricky and is not guaranteed to work in all cases.