I just upgraded my mid-'10 MBP to Mountain Lion yesterday (clean install). Everything went well with the install. However, I have an issue. When the computer is not connected to my ACD, it sleeps as it should when I close the lid. But when it's connected to the ACD, it won't sleep; instead, it switches my external display to be my main monitor and the computer remains awake. Ideas? I want it to sleep when I shut the lid when it's connected to the external.