Try recreating the users configuration folder as outlined in step 12 of the Adobe troubleshooting guide:
The in the extension manager, uninstall the extensions, and install them again.
Make sure you install the Server Behaviors panel extension first:
after that one is installed, open DW and close it before installing the others.
after installing eCart and Data Bridge to the extension manager, open DW and a PHP page start the WebAssist installer. When the WebAssist installer completes, don't forget to restart DW.