I was using free anti-virus software from Microsoft (Microsoft Security Essentials), and I discovered that the software eventually stated that it was out of date. I noticed that often when I typed a web address in my browser the computer was directed to the wrong web address. It would take a number of tries before I was directed to the correct web address. I purchased new anti-virus software(Norton) but the problem persists. Do I have a computer virus? How do I correct the problem?