I have OneNote 2007 on a Windows 7 desktop and OneNote Mobile on a Win 6.1 HTC HD2. ActiveSync works fine for all items apart from OneNote, comes up with Sync Error - Microsoft Office OneNote: attention required. Usefully it doen't tell you what attention!. I notice in other posts that there should be a Mobile Folder in OneNote 2007, there isn't. I have reinstalled from OneNote 2007 to the HTC. I have also created a new note on the HTC, but doesn't appear to help. The datafile location for OneNote 2007 is not the standard one, actually in a Folder CUsers\RJB\Documents\Data\OneNote Notebooks\My Notebook\. Help gratefully received.