Haha! Norton, the antivirus-eater. It always blocks any new attempt to install programs, especially another antivirus.
I'm sorry but there is nothing much you can do if you won't be able to uninstall that Norton antivirus. Just let your dad uninstall the Norton and install a working antivirus (which can be disabled whenever you want). Don't tell him you will install the RFO if it will make him angry and do it by yourself. Lols!
Make sure you downloaded, installed and updated the RFO client WHILE YOUR ANTIVIRUS DISABLED. You will receive these kinds of messages because of missing files which are most probably deleted by the antivirus during the said processes.