Symantec Norton can be a bear to uninstall and get rid of its stray files and registry entries.
Go
here and download the
Norton Removal Tool.
Close all open windows, then run the tool.
Restart your computer after it's done.
----------------------------------------------------------------
Unless you're insistent on using Symantec Norton, there are plenty of good anti-virus programs out there. And some of them are free.
The top 3 in
this list are free and are the most popular ones.
If you prefer a "paid" anti-virus program, Eset NOD32 gets good reviews in these forums.
---------------------------------------------------------------