I am at the safe for "red mercury". Icon has a lock which looks 3/4 closed. I engage safe cracking. Window appears with lock but I have no directional key control. Tumblers will not turn. Your help would be appreciated. Thank you.

The problem is a leftover artifact of the XBox360. With the 360 controller the tumblers won't move unless you push the analog stick to the full extent. This coincidently is the same as full speed when you are walking or creeping. So in order to hack the safe you need to make sure you roll your mouse wheel all the way forward, as if you were to make Sam run, and then you can open the safe cracking window.

Good luck, you will need it as the game goes even further downhill from there.