So, I have been playing Act 1 a 4th time waiting for the patch that stops the game using 3.8GB of RAM in Act 2 compared to 1.8 GB of RAM in Act 1.
Now I have found the strangest occurrence - the Key you get on the stool from defeating the Hound Master suddenly doesn't work on the doors in the Hound Masters quarters - 3/3 times this key was sufficient, suddenly, I cannot get to his fancy crossbow.
Much Sad.
