I downloaded Windows 8 RTM from MSDN (I have a subscription). Naturally, I downloaded the product key as well.
Windows 8 installed like a dream: lightning fast with no problems. I accepted the product key at the beginning of the install.
Next, I thought I would download Updates, but they failed, so I checked the system's activation in Control Panel > System.
Problem: It returned "Product ID: Not available."
There's nothing under "Windows activation" that I can click on, no blue links.
I had a 'Chat' with MSDN, who introduced me to SLUI.exe. On Windows 8 it did nothing. (On Windows 7 it is supposed to bring up the Activation Menu).
I phoned the Microsoft Activation number, they told me to contact MSDN. MSDN left the 'chat' by telling me to contact Microsoft! Hmm… I wonder if anyone at SuperUser can help?
I am now convinced it was a hardware problem - probably disk corruption.
Clue 1) SLUI does not run - The file exists, but it's likely corrupted.
Clue 2) I remember now, this machine has given problems since day 1.
Clue 3) Nobody else is getting a problem installing and activating Windows 8 RTM.
Confirmation. I installed Windows 8 using the same ISO medium and the same product key on another machine. It activated perfectly.
Thanks for again for the forum members' support, your ideas and suggestions propelled me to keep trying until I found the answer.