I had a problem with my laptop where the lcd on the monitor does not always work, presumed to be due to a loose inverter cable or something similar to this. As a temporary solution I have been using an external monitor for the past few days. Depending on whether the laptop lcd is working, I have had it on both mirrored and dual monitor settings. However, this evening when I have come to use it, the external monitor is now the only one that is working. Options to turn off mirror display have now gone. Also, the button on my mouse pad no longer works, yet the pad itself does. I have come to the conclusion that my laptop is in 'clamshell' mode. It remains on, and does not sleep when I close the lid. I have put it to sleep form the apple menu, disconnected the external monitor, and the opened the lid again, and when it turns back on from sleep, the screen flashes on for a second, but then goes to sleep again. I have tried turning it off, restarting, taking the battery out, everything I can think of, but unless the external monitor is connected it almost immediately goes back to sleep. Any ideas guys?