Charles provided a link for starting in Safe Mode. Try opening one of the problem documents after downloading a copy from Sharepoint. Then open Word in Safe Mode and use File > Open to open that downloaded file. If you can make edits without a freeze you will have a clue as to where the problem is coming from.

Post back with your results from testing with Safe Mode and we can provide some steps for disabling templates to figure out where your problem is coming from. Most of those steps are described in Charles' first link.

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Andrew Lockton
Chrysalis Design, Melbourne Australia