I am at a bit of a loss on this because I never use this feature. I wasn't really aware of it. I never distribute Word documents unless I want them to be edited by the recipient; I use pdf. I may start using it for when I do send Word documents.

What happens if you start Word in Safe mode?

If it works in safe mode, I would suspect a poorly written Add-In.
See Add-Ins in Microsoft Word.

This feature would be especially important if I used one client document as the basis for a document for another client. I almost always start my production work from templates that don't hold client information.