I also had problems with entering the keycode on the taleworlds site. After playing the demo, I ended up buying the game via Amazon, and then used the manual registration because my PC at home doesn't have internet access. The taleworlds site kept telling me "invalid code", and when I tried the Hardware Hash instead, it said "invalid format". I emailed tech support.
After about another hour of fumbling and futzing around here on the forums looking for answers, I spotted an alternate link to taleworlds.net in one of the stickied threads, rather than the standard link to the .com site. That brought up a screen with spaces for both the keycode and the hardware hash, and it accepted them, displaying a full activation code. I'll try that tonight, but at least it's looking like progress toward getting the game activated.
Hopefully, this will save someone else about an hour of frustration.
[ That works. Just change the taleworlds.com/act/ to .net/act/ in your browser and it should take you to the activation screen,or use the link in the sticky topics at the top of this forum. ]