have you tried Deleting the Dreamweaver Cache file from the users configuration folder:
If the problem continues, try using Universal Email on a blank php page to see if the problem is being created by something specific to the page you are working on.
if you don't have a problem using Universal Email on a blank php page, send a copy of your page so I can investigate what on the page may be causing the problem.
Also, i'll need some details about your environment.
what version of Dreamweaver are you using?
What is your OS?
What WebAssist Extensions are installed, including the version numbers?