These are few problems which may be may arise while using the Norton antivirus. When you find any of these problems or some other problem without much delay you should contact Norton customer service team for help. Suppose you suddenly find that filter plus does not recognize a virus that it means that it will definitely allow it in the device. If by chance this virus enters then it can harm your device. Therefore, you have to ensure that you make appropriate changes in the filter plus from time to time so that the filter plus is able to recognize the respective virus on time. If you need any help for doing so, then you have to avail help of support team for making the required changes.