reset the workspace layout:
go to Window -> Work Space layout -> Reset '<your layout name>'
then Delete the Dreamweaver Cache file from the users configuration folder:
http://www.webassist.com/tutorials/Common-installation-issues
and restart the computer.
NOTE: you can export your presets using the preset manager ( Webassist -> Preset Manger) in the event that you need to uninstall and reinstall the extensions.