Microsoft Word runs in the Background

Every time I re-save an LibreOffice Writer document (odt) the task manager shows "Microsoft Office Word (32bit) starting up in the background.
Occasionally during a save, I will get an error from Word saying the odt file is in use.
All this without ever running Word in the foreground.

Using LibreOffice 5.2.7.2.
Any ideas how to stop Word from running ?