It sounds like a privilege problem but the strange thing is if you didn't have the appropriate privileges then it should not have allowed you to install norton.
If you go into Control Panel and then double click on "User Accounts"
Check what group is listed under you login name, (it needs to be set to Administrator)
If it isn't then you should be able to click on Properties and change it to Administrator from there, otherwise Add another username and make sure it is set to Administrator.
This link might help
http://uis.georgetown.edu/software/d....accounts.html
Hope this helps