Get
RegCleaner which is invaluable & (free)
http://www.vtoy.fi/jv16/shtml/regcleaner.shtml
under the Software heading (1st page) remove everything relating to Norton\Symantec
Check startup (2ndpage) also.
Under Uninstall (3rd) remove norton.
Manually remove all files relating to norton\ symantec in explrr.
This is a dirty uninstall.
Run the registry cleaner (in tools)
although i would use for cleaning the registry:
Registry healer
which allows you to manually check which errors to fix and where and how.
http://kslsoft.virtualave.net/regheal/index.htm (demo)
remove all relating to Norton\Symantec.