Norton Antivirus 2005

Hey,
I work at a Computer repair shop and the only thing we use is what we get from our suppliers which is now only norton antivirus 2005. and im having a problem with a computer for almost a week now that i would like some help with if anyone knows anything about it. When i installed nav 2005 it installed fine and the computer gets on the net fine. it has no spyware no adaware and no viruses on it, but when i try to activate nav 2005 the program locks hard. any ideas as to why that may be (please keep smart ass answers to ones self)

Eviltesdall
eviltesdall at hotmail dot com