I use a MacBook Pro (17-inch, June 2009) with the display, and when I my connect the display it occasionally dims on it own. The HUD shows the display dimming and none of the buttons seem to work. I double/triple checked the settings in System Preferences, and the buttons aren't disabled. It only happens occasionally, so I fear if I pack it all up and take it to my local Apple Store, its not going to happen there, and nothing will happen. Anybody ever experience anything like this?