Word crashes with documents with "track changes" on
The problem is not with the track changes and comments but how Word tries to display them: in a Balloon... 

Luckily there is a simple solution:

Word -&gt; Preferences -&gt; Track Changes -&gt; "Use balloons to display changes" 


remove the tickmark from here.

You can still see the changes inside text by checking the colors and use 

Review tab -&gt; Comments -&gt; Previous, Next


to step through comments (the list will be opened at a left side sidebar). Convinient way although not so fancy, but at least: it works!