Bugger. That Word line break issue happened to me once, and I can't remember exactly what caused it. I *think* it's something to do with copying and pasting, where Word creates some weird style from the pasted in text and then anything which you type into the area ends up with the same crappy formating -- basically, it's faking line breaks but there aren't in fact 'real' breaks there when you copy and paste out again.

Try selecting the whole document, then setting the paragraph style to normal.