Solving this Error: Your message cannot be sent because your message has been changed.

My understanding is that the whole point of the Outlook draft folder is to be able to store an email one is drafting and editing in stages.  But now every time I do this (did not happen a few years ago), I get the above error message.  How can this be?  The only work around is to cut and paste the final, ready to be sent email into a new email window, and delete the one in the draft folder.  This is cumbersome and seems to defeat the whole point of the draft folder.  Please help.  Is there a workaround to this error that wastes time?  Thank you!