Outlook 2013 Update Problem
Today Microsoft pulled an Office 2013 UI update for Outlook (KB2817630) from the Windows update servers. The update was meant to improve usability of Outlook 2013, but in certain conditions rendered the Navigation pane in Outlook unusable.
The update KB2817630 applies only to Office 2013 and is unrelated to security bulletin MS13-068, which applies only to Microsoft Office 2007 and 2010, and which we continue to recommend as a high priority security update.