Thank you again
The problem arose because Free Tools tried to uninstall where at the same time one of DMXzone extensions tried to update. So after having killed Dreamweaver I deleted every WA extension, updated the DMX-zone ones and after this re-installed the WA extensions, including eCart again. So, everything is working fine now, but I am aware that the next DMX-zone update might have the same conflict again if DE and DB have not resolved their issues.
So, thanks again, for offering help. Since the time difference is quite big I am happy there is no necessity for a phone call at the moment