Yesterday Microsoft released an update for outlook. They stuffed up and it forces outlook to open in safe mode. If this happened to you too then go here http://www.infoworld.com/article/3013219/microsoft-windows/microsoft-pulls-botched-patch-kb-3114409-that-triggered-problems-with-outlook-2010.html and uninstall the update. Microsoft has now removed the update so if your computer didn't update yesterday you won't get it. Outlook safe mode has no add-ins and no preview panel. I have windows 10 but not sure if that's the only version of windows effected. Just thought I'd let others know as it took me a while to source the issue. I think it only effects outlook 2010.