Microsoft released a botched patch on patch Tuesday (second Tuesday every month).
Look out for KB3114409, it was meant to give administrators better control to stop Outlook 2010 from opening in safe mode. However it did the exact opposite, causing Outlook 2010 to only open in safe mode. You can tell if Outlook is in safe mode by looking at the top of Outlook, it will say, “Microsoft Outlook (Safe Mode).
To remove the update, go to Start->Control Panel->Programs and Features->View Installed updates. Then search for KG3114409, right click and uninstall.
Microsoft has pulled the update as of Wednesday morning, so it won’t reinstall next time Windows update runs.helpdesk