I recently purchased another 27 inch iMac (Late 2011) to go along with my 27 inch iMac I already had. I connected the second iMac to the first one with target display mode to use it as an external monitor. However, when sleeping the first iMac either by pressing the power button or clicking the sleep button, the second iMac becomes disconnected from the first iMac! I have to enter Target Display Mode every time I wake up the first iMac so they will be connected again! Is there any way around this? Or am I doing something wrong?