If you've upgraded to OneNote 2010 but some of your collaborators or potential readers have not, you'll need to convert your shared documents to be compatible with OneNote 2007.
This is actually pretty easy to do, though the feature is a little buried and can be hard to find when you're tearing your hair out right before launching a mission-critical playbook or user manual. Here's how to do it:
1. Open your OneNote notebook in OneNote 2010.
2. Click the File tab to open the "Backstage" section.
3. On the Info tab, you'll see Notebook Information for each notebook you have open (scroll down if needed to find the one you need to convert). Click the Settings button for the notebook you want to convert and select Properties:
4. On the Notebook Properties dialog, click the Convert to 2007 button:
You will see this warning (and you can cancel if these features are needed for your project!):
If you click OK, your notebook will be converted. Check the conversion, prepare it for distribution, and then post it to your SharePoint or other shared location.