I don't know anything about your setup but firstly I would check that you are actually saving the files in docx format and not html.

I haven't see documents randomly change their view when opening so I would be checking to see if there are any macros that might be running that is causing this behaviour. What template is attached? Is there code in your Normal.dotm? Is there any addins installed?

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Andrew Lockton
Chrysalis Design, Melbourne Australia