Darkness 说:
That one is simple. You either A) Entered the wrong CD key when you downloaded and installed the game from the one you entered to get accepted into the beta, or B) you DLed the beta installer from some third party source and did not actually get accepted into the beta
I didn't do either of those things. I downloaded .500 from the link in my email and it didn't ask me for my serial key. Then I downloaded the .510 update by entering my email and serial key, and then the same with the .520 update.
Edit: I downloaded the full .520 setup using my email and key, uninstalled Warband, reinstalled using the .520 setup and the problem still occurs. I don't know if this is actually a problem with the game or just me but I thought I'd might be helpful to share this issue anyway.