That is odd. Converting a spreadsheet into a PNG sounds like something a browser would do to a file.

I really have no idea but I would ask - has the Word file been saved into a tool like Sharepoint and viewed/edited in a web browser. I have not had joyous experiences with ill-informed people editing Word documents via a web browser instead of the native application so I am thinking this could explain an intermittent reason why this conversion could happen.

If this is the cause, I would say you need to revert to a previous version to restore the content to spreadsheet.

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Andrew Lockton
Chrysalis Design, Melbourne Australia