Don’t install more than one anti virus software on your computer. The mantra two is better than one doesn’t apply to anti virus software. The second anti virus software will add more overhead to your computer and slow you down even more than the first will. “The two [programs] will complain about each other and have a little anti virus fight,†says Cargill. “McAfee may detect something that Symantec is doing and think that it is virus-like activity and try to quarantine it. As soon as McAfee tries to quarantine Symantec, Symantec will think a virus is trying to remove it and try to quarantine McAfee. Then your computer gets [stalled] and you don’t know what happened.â€