Have to come back to this old message since I have exactly the same problem. I have done the following operations and the problem happens still once a week:
- complete reinstall of machine from scratch (Office 2010)
- updating to Office 2013

So repari does not help. Must be related to my way of using word. Might be also that the problem is only with my own templates???

What has helped is to wait and then select "End task" from Windows Task manager (not end process). This will wake up Word and give possibility to say Cancel.

Before this Word does not respond to any request and uses app. 25% CPU time.