Just upgraded to Windows 10 and had the Norton 360 disappearing problem initially but worked around that although the fix was a bit painful (the uninstall/reinstall utility did not work). Then I had the following show stoppers:
1. An exe file that I trust was repeatedly removed and I could not find a way to restore or sanction the file.
2. After the removal the Norton error process just keeps running and prevents W10 from sleeping. Only way around this seems to be to re-install.
So for now I have uninstalled N360 and am relying on Windows Defender.