That error has been reported and there are a few work arounds, but no definitive answer. In this case, let's skip that step.
Make sure you have all the downloads done before proceeding.
Post back after Norton is installed. If it installs and runs, then do a complete scan with it,.--
When angry count four; when very angry, swear.
Microsoft MVP/Consumer Security 2005-2011
Gladiator Security Forum