Had an issue where a customer started having issues setting OOF on a remote Exchange server 2007 when using Outlook 2013. After some digging arround and making sure all autodiscover settings and SSL settings were accuratlly set I stumbled across the issue where installed hotfixes were causing the problem. The culprit is a faulty set of updates recently pushed out by Microsoft. To be specific, the following hotfixes are Outlook 2013 (KB2837618) and Microsoft Office 2013 (KB2837643). They have to manually be uninstalled and a PC reboot issued to fix the problem.
This is for only Outlook 2013 and Exchange 2007 that I am aware of currently, others maybe affected so use wisely.