Close DW and recreate the users configuration folder as outlined in step 12 of the Adobe troubleshooting guide:
Then open DW, go to Commands -> Manage Extensions to open the extension manager.
After the extension manager opens, close DW.
In the extension manager, uninstall the extensions, then use the Install button to browse to the MXP Files to reinstall them.
after they are installed in the extension manager, open DW to start the WebAssist installer.