As already pointed out, we need to see the actual document to solve this but my prediction on what is going on here is...

All the paragraphs have both Widow/Orphan Control and Keep with Next turned on. That is why you are seeing breaks in the middle of paragraphs that are at least 4 lines long.

If another machine doesn't demonstrate the problem then I would say the document has the Template styles automatically updating on open and the template attached to the document has a different paragraph settings for that particular style on that machine.

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Andrew Lockton
Chrysalis Design, Melbourne Australia