Tips and Tricks: Solving the Common Error in Activating Windows Vista
This should help you solve errors with DNS not found messages encountered when activating Windows Vista, a lot of them where expererienced through VPN.
This thread (found here) should guide you to the right path Windows Vista.
In any case running this code may solve the problem as well

br />
cscript C:\Windows\System32\Slmgr.vbs -ipk [Product Key Here]
cscript C:\Windows\System32\Slmgr.vbs -ato
http://feeds.b5media.com/~r/b5media/.../~3/108926930/
Sat, 14 Apr 2007 00:55:48 +0000