reset the workspace layout:
go to Window -> Work Space layout -> Reset '<your layout name>'
and Delete the Dreamweaver Cache file from the users configuration folder:
http://www.webassist.com/tutorials/Common-installation-issues
If you continue to have a problem, please provide additional details:
What is your OS?
What Version Of Dreamweaver?
What Version of eCart?
What other extension including the version numbers are installed?