There's some talk about Norton removal tool here
http://community.norton.com/t5/Norton-I ... d-p/532112 , sounds like something can be left over after uninstalling it.
Also try running the RWR installer as an admin user if your user account already isn't one.
You could also try to install the game somewhere else than under Program Files folder.
Using Desura you might not have this issue as it uses another way to install RWR, you could give it a try at least.
RWR will also become available in Steam soon and you'll receive a Steam redeem key. Steam will thus provide yet another way to install RWR.
You can of course get a refund if the game isn't working for you. Desura handles the refunds.