Norton is one of the worse anti virus programs out there. I had it one time and kept chewing viruses. I changed to Avast (which is free) and never had a problem after that. Also ad a good firewall like COMODO and a good real time spyware program like Spyware Terminator. All of these are free and you can find them at cnet.com.
I can send any of my computers in the bowels of hell and come out clean as a whistle!
Billy