I just switched text editors to something that fit my needs better, and it seems External Editor is having serious problems working with it -- but only part of the time.

If I click on the toolbar button to open the email in a external editor (in my case, "Crimson Edit") it carries it over there just fine.  I type my email, then close the editor.  Here's the problem: sometimes the text appears over there just fine, but sometimes the text flashes for a split-second in the compose window then vanishes, losing my work! 

External Editor works just fine if I use other editors, and Crimson Edit works just fine in general... It's just that *something* is going wrong when the two are put together.  I don't want to use another editor, because so far Crimson is the only one with the features I need.  Here is the program website if it is useful to know:
http://www.crimsoneditor.com/