can not access mozilla firefox internet web site when norton security is on

When I have converted internet access from Internet explorer to mozilla firefox I was able to access to internet without any problem. On that time I was using Mc Caffee security system. Later on ny computer the got virus, I cleaned up my hard drive with the help of HP people. This time I used norton disk for security; because I had the disk from them. Now I at not able to access to mozilla firefox web site. Accessing is possible only If I turn the security system off. I know this is not a healthy way of accessing internet. I had bought and downloaded Mc Caffee thru the Internet. During the cleaning up of my computer that program was also removed from the hard disk.When I sent email for the help they didn't give me any respond. I have "Norton Internet Security" and "Norton Goback" in the computer. One time I have removed the only "Norton internet security" and downloaded back. Still I have the same problem. I will appreciate very much If somebody helps me.