One a month something happens in Norton to prevent my Windows 7 64 bit machine from accepting connections and shares. This machine can access every other computer on the office network but if you try to access the Windows 7 machine you get a "you don't have access" message. The fix is always the same, bring up Norton and "reset" the firewall. There is a place to do this on the firewall page. The word "reset" is underlined and just click it and you are good to go for another month.
I don't know why this happens but am posting this to help anyone else who may experience this.