Ouch! I thought it was auto updating!
My Mac's on El Capitan, version 10.11.6
I recently obtained Office 2016 for the Mac, and it has an Autoupdate "feature". I had been using Office 2011 for a number of years, and never actually saw such a feature. So, I had to manually check myself for updates (in fact, prior to my post above, I needed to manually check for V14.7.0, as when I upgraded, I was last on V14.6.9).
I of course do not know if upgrading to V14.7 will solve your issue, so I would recommend you repair disk permissions. For that, you need to download the excellent freeware program Onyx, which you can get from here:
http://www.titanium.free.fr/onyx.html
As you can see, there is a specific version of Onyx for each Mac OS, so since you are using El Capitan, make sure you get V3.1.8. I have been using Onyx for many, many years, and it is stable, good at what it does, and has had excellent reviews. In fact, prior to upgrading this past weekend of Sierra on my Macs, as I usually do, I used V3.1.8 for the last time, and as expected, it worked.
After you install it, do not launch it immediately. The reason is that it will not pass by Apple's Gatekeeper. Instead, right click on its icon, and select Open. I believe it will ask you one additional question, and then it will start up. You'll need your "admin" information (ie, password) to get it going. Let it check your disk (that is the first question you'll be asked). Then, click on the "Maintenance" Heading, and select Permissions. It will take a couple minutes for that to complete. Finally, run it immediately again.
By the way, are you making backups to an external device? And, have you done any disk cleanup/maintenance/repairs? Both of those tasks are necessary, and you should be performing them on a periodic basis.
