If you find that Outlook 2010 now opens only in safe mode, it may be because you installed update KB3114409, which was released on December 8, 2015.

Microsoft released a new update on December 16, 2015, that includes the fix for Outlook 2010 launching in safe mode.

Use this link to install the new update: December 16, 2015, update for Outlook 2010 (KB3114560).