Assumming the firewall was OK prior to the ram upgrade then obviously whoever did the upgrade has caused the problem. Just upgrading ram would not affect the firewall so I wonder what else they have done? They may have used the computer and/or played about with various firewall settings such as denying IE internet access. Also make sure you do a virus scan.
Is it just Norton personal firewall you have installed or is Norton Internet Security? I have only ever used NIS but possibly what I am about to suggest might help. You mention trouble with "Live Update" after reinstalling. When you uninstall any Norton product with the intention of reinstalling and that product uses "live update", then it is absolutely essential that from 'Add or Remove programs' you not only uninstall the product but also uninstall "Live Update", "Live Reg" and also "Norton WMI Update" if present.
If you don't remove all components you won't get a successful reinstall. You will definitely have problems trying to use "Live Update" with various error messages being displayed. I have tried other security products, (usually the freebies)out of curiosity, and then come back to Norton without any trouble on the reinstall. I have also done uninstalls and reinstalls on friends computers without any problems by following the above procedure.
I seem to have rambled on and said very little but hope it helps.