Today we released a non-security update for OneNote 2010, here are the details from the Microsoft Office SE blog:

A non-security update for OneNote 2010 32-bit/64-bit Editions was also released.  This update provides fixes associated with displaying search results, fixes to optical character recognition (OCR), indexing, and displaying of inserted documents.  Additional information can be found in the Microsoft Knowledge Base article Update for Microsoft OneNote 2010 (KB2493983). 

We heard a bunch of people mentioning this on the OneNote Answers Forum and we were able to figure out the problem and get a fix out for you all.  We apologize for this inconvenience and encourage all users to upgrade today to fix up any issues you might have.  Thank you much and please let us know if you have other concerns/issues!