I can't think of anything else that we can try at the moment.
If this does not work and you did not remove the disabled extensions, you can restore the previously backed up configuration folder to enable all your extensions again.
Here are the steps you should try:
1) Close Dreamweaver and Extension Manager
2) Navigate to and rename Configuration folder to Configuration_back
3) Start up Extension Manager (extensions should be disabled at this point).
4) Remove the DataAssist extension.
5) Make sure you have the latest version of the DataAssist mxp file and install DataAssist.
6) Open Dreamweaver and test DataAssist Wizard.
At this point, if DataAssist Wizard works, you will have to re-enable the extensions one by one. If it doesn't work, follow these steps to revert back to your previous setup:
1) Close Dreamweaver and Extension Manager
2) Navigate to and delete Configuration folder
3) Rename Configuration_back to Configuration
4) Open up Dreamweaver and check to make sure extensions are restored.
