I am certain that the ISO I downloaded is official as the SHA-1 hashes matches the one released by Microsoft. I have also used the disc to install a new copy in a virtual machine, and the Help and Support issue did not occur there. I have searched the internet about the issue, and seems like Windows Vista was previously having the similar issue caused due to the xml handling by Dreamweaver 8. However, that fix does not work in my Windows 7 installation in this case.
Regards
Plexion