As you said in a comment (just writing this answer for anyone who stumbled upon this question), the keyboard turns off when you are in full screen mode.
This is due to security restrictions, because someone can create a swf that replaces some actions on your computer ... for example, displaying a desktop that has a dialog asking you to enter your live ID and password. There are probably many other sinister uses that adobe needs to avoid by disabling keyboard input. I am not afraid of this.
J
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