Install Fails with Registry Key Error

The update to the latest version fails to remove the previous version and ends with an installer error. I have checked the Windows Installer database for errors, and managed to remove the previous version.
The new version still loads but there is no trace of it in add/remove programs, the program directory is still there under C:\Program Files (x86)\eM Client.
I have tried re-installing the latest version (Version 6.0.24144.0), but it fails with a registry key error:
Could not open key:
UNKNOWN\Components\1B00334CCC99D764A8AEF25ADBB955B6\0D1F56FCB154989449DB2C73FE94C254. Verify that you have sufficient access to that key, or contact your support personnel.
I have tried taking ownership of that key in the Registry Hive, but it makes no difference, the error is still as above. I have deleted the key and the same message appears.
I have run the System File Checker and it had validated that all problems have been fixed, but still the same error appears.
The computer is running Windows 10 Pro, latest version fully updated.
Other programs install/uninstall correctly, so it looks like a problem with the EN Client MSI installer?
Is there a comprehensive removal tool available as I would like to get this uninstalled completely. EM Client is not my main Email client, I have it installed purely so I can test it for our clients.
Any ideas?

you should be able to uninstall the program using the installer of the version you were running before.
Here is the MSI for the previous version 6.0.23421 -…
Also, if this does not work, can you try installing again the newest one and create installation log using “setup.msi /Lv* log.txt” in the Windows command line and send the log.txt to me at with a link to this forum thread in the message of the body?