I've been using Norton 360 for a long time and not too long ago I noticed Norton hadn't started with the computer.
I got the error messages 8504 & 104. I followed the instructions (I was redirected to the Norton website to reinstall the product).
The fix worked for two boots. Now whenever I boot my PC Norton doesn't start [task manager shows Norton running but there is no tray icon and no way to access the GUI] and I have to restart my computer for it to run on startup.