I have run Microsoft Office Diagnostics, as recommended, and have got no results. Also, I have tried to install instant search from the Options window, but that button is grayed out. There were no errors given during the installation of OneNote, and Microsoft Windows Desktop Search was installed prior to when I installed OneNote. Any help is very appreciated
OneNote is not properly registered for using Microsoft Windows Desktop Search and cannot index notes for Instant Search. You can repair the OneNote installation to fix the problem.
On the Help menu, click Office Diagnostics, click Continue, and then click Start Diagnostics. Restart your computer after the diagnostics have successfully completed running.