Just a FYI for all you Neowinians........ I encountered this problem tonight. After downloading and applying today's Windows Updates, the folder view in Outlook 2013 shows a blue column with the folders obscured. Had to uninstall the update KB2817630 to correct the problem.
One of the many updates served today to users by Microsoft through Windows Update is causing problems for users running Office 2013.
The update, labeled "Update for Microsoft Office 2013 (KB2817630) 32-bit Edition" or "Update for Microsoft Office 2013 (KB2817630) 64-bit Edition", contains bug fixes, and stability and performance improvements. After applying it, many users are reporting on TechNet that the Outlook folder pane is left empty. Many are also reporting that uninstalling the KB2817630 update fixes the problem.