You stated your question well, Dave, so that's not a prob. .

I'm wondering, within your CP or user Control Panel and Edit Options, what do you have selected under the Miscellaneous Options and Message Editor Interface? It's the last set of options in your CP.

Mine is set to Standard Editor.

You might try changing yours to a diff. one and see what happens.

I can't remember which option it is, but when I used a different (other forums), I also had posts which broke sentences where I hadn't intended for breaks to appear.