See bug 1409 -- I recall that this was discussed extensively on the ML circa 2008/2009... It took a LONG time to get it resolved. Today, had the 3rd or 4th occurrence in the past few months -- write a paragraph, go back and do some rewording and auto-wrap starts making the paragraph look like this... I was going to provide a pointer to the ML archives; but they only go back to 10/2011... I still have most of the messages from back then if that helps... Preferences->Compose->Wrapping: all on & 74