Dash - I think this worked for me... eventually. Here's what I did. I couldn't get anything to unlock DA in single player yesterday. So, I uninstalled and redownloaded the game. This didn't fix it for me. Then I tried to run the game as admin, as you suggested. That DID NOT fix it for me either. Then, as a final step, I hosted a MP game, selected DA, then just quit the lobby (without every launching the game). Then, I went back to SP and I was able to select DA in skirmish and tournament. So, I think its a combination of things.
So, my advice to anyone still having issues unlocking the demon assassin in SP would be to.
1. Run the game as an administrator
2. Log in to multiplayer and host a game. Select the Demon Assassin as your playable character. Then exit out of multiplayer
3. Go back to single player mode and check. DA should be unlocked
Thanks for the additional info Pacov! So far from reports it sounds like a combination of things are working for those that didn't have immediate access to the Demon Assassin in single player. If anyone still can't access him after trying all of this, please drop an email to firstname.lastname@example.org and we'll get you sorted out.
Can't wait to surprise my friends at our annual Thanksgiving LAN party - they don't know about the new character yet, and probably won't have him unlocked after patching. Heh-heh-heh...
That's just mean.