This error is currently being generated by AVG AntiVirus (v16.141.7996) – so, if you have an AVG security program installed, this will be the cause. Switching off the "AVG Self Protection" feature (Options → Advanced Settings) stops the errors.
The program generates Event ID:7006 errors in the Windows "System Event Log" – showing an Error (using the Red "!" symbol) – twice during startup of Windows and once during shutdown. It appears that the "AVG Self Protection" feature is blocking access to certain AVG Registry entries that AVG itself is trying to update.
AVG appears to function OK despite the registry access errors – but it doesn't inspire confidence when a security program generates these types of errors accessing its own registry entries. The problem has was reported to AVG several months ago – we are still awaiting a fix.