A family of Microsoft products that enable users to capture, organize, and reuse notes electronically.
Update: I tried typing "Onenote /safeboot> Clear cache" and running as an administrator a couple more times, and then the last time it opened it up and all the notebooks were closed (as it appears was expected), so I opened them all again, figuring the problem was fixed. Then to test it I closed OneNote again and tried to open it. This time I got a message that said to please wait because OneNote is cleaning up from the last time it was open, and there was a status bar. Once the status bar filled, I got the same "OneNote can't open" message again.