OneNote is unable to start because another instance of OneNote is already running. Click OK to exit OneNote and then wait ...

OneNote is unable to start because another instance of OneNote is already running. Click OK to exit OneNote and then wait a few moments before you try to restart OneNote.  Note: If you are running OneNote on a Microsoft Windows server operating system and you have logged in multiple times through remote sessions, you can run OneNote from only one of these sessions.