Yesterday (December 9th, 2015) Microsoft rolled out a faulty update for Microsoft Office 2010 (KB3114409) which accidentally causes Outlook 2010 to start in safe mode systematically, ignoring registry and computer settings.
To solve the problem, simply go to the "Programs and features" control panel applet, click on "View installed updates", search for KB3114409, and uninstall it. After you reboot your computer, Outlook will start normally again.
This solution has been tested successfully at work for dozens of users.
Microsoft stated: “After you install this update, Outlook 2010 may start only in safe mode. If this issue occurs, uninstall the update. This update is no longer available now."
Source: Microsoft message boards