Norton updates that do not complete,
what I have is a question to Apple as to how long do you have to fix before you have to replace?
Apple is not responsible for third party software installed on your Mac that may cause incompatiblity issues.
Running Symantec's Norton a/v software on a Mac can only cause problems.
Check out the results of an ASC forum search for Norton > Community Search: Apple Support Communities
If you feel the need to run a/v software on your Mac, uninstall Norton > Uninstalling Norton AntiVirus | Macworld