Hi,
I followed the suggested solution of using Norton remover and re-installed Norton 360 (I had done this before posting the question but went through the process again).
Windows file check also did not return anything and I kept on getting the same error.
I invetigated further and noticed two folder under C:\ProgramData folder. This is a hidden folder so needs to make it visible. one folder is "NortonInstaller" and "Norton". These folders has many files including log files sub-folder. these folders were not removed by Norton remover so just to make sure all old 'Norton' references are removed, I renamed both the folders.
I removed and re-installed Norton360. It has started working again (hopefully will keep on working now - just 10 minutes since finished re-installing :-) ).
Best regards