This sounds strange. I originally got the Cyberdefender free scanner which cleans Trojans and spyware for free, but you got to pay for the upgrade for virus. So I used it for checking. Eventually I got a virus - a bad one called virtumondo, and bought the upgrade. Since then no problems. Cyberdefender caught a few trojans and one more virus attack, and it worked great. The upgrade I got includes 24/7 computer help, which my wife needed once when I was away on a trip. So, I hope this helps, it is just my unformal review of my Cyberdefender experience.