Fatal Error message

[Romulator]

1. This is in the wrong section of the forums. No biggie because a moderator will move it.

2. Well assuming you have 10.9 Mavericks, Amnesia is incompatiable with that at the moment. When you mean the update, I am also assuming that is the Amnesia 1.2 (Justine) patch, which like I said, is incompatiable.

Could you run a Steam Integrity Check if your game is on Steam to find if there are any issues with the installation?
Also, did you download your Level Editor and other Development tools from the Wiki section? There are a few methods there which you may or may not have overlooked. I, being a Windows user, can only really support up to there however.