Stefan Kueng - 2016-02-29

Onenote can run under a different user account, for example as Admin. Use the task manager and look for running onenote processes (show processes for all users in task manager to see them all!).

That error message is shown if the COM object for onenote can not be created.
And your error clearly states that the COM object isn't even registered (see the "REGDB_E_CLASSNOTREG" result). Which means you either don't have Onenote 2013 or 2016 Desktop installed, or not properly installed. In which case you have to do a repair install.