Followed these step but still getting the same error.
I also tried making sure Dreamweaver is running with elevated permissions but still gets same error.
Tried again, and followed these steps
1. removed Design Extender Extension
2. removed folder %appdata%\Roaming\Adobe\Dreamweaver CS6
3. removed reg key HKEY_CURRENT_USER\Software\Adobe\Dreamweaver CS6
5. Added extension using extension manager
6. started Dreamweaver CS6
7. produced same error????? :(