You have a conflict in having both Universal Email 4 and Digital File Pro 2 installed.
UE 4 contains the DFP Functionality, that conflict could be the cause of the problem.
I would recreate the users configuration folder as outlined in step 12 of the Adobe troubleshooting guide:
http://helpx.adobe.com/dreamweaver/kb/troubleshoot-javascript-errors-dreamweaver-cs4.html#main_user_config
then uninstall all extension from the extension manager, restart Dreamweaver and close it, then reinstall the extensions leaving Digital File Pro out.
where eCart 5.0.7 is the most recent release, install that one last.