Since installing Mac OS X 10.6.4, more often than not my MacBook Pro refuses to wake from the sleep that's induced automatically once it's been disconnected from my 24" Apple LED Cinema Display. Little infuriates me more than when I have to power-cycle a machine to get it back. It's just not an option for me and my workflow.
After I experienced this twice in a row (it doesn't occur every time, which only makes it more annoying), I stopped everything and decided to figure out a way around it. An absurd way around it.
The following is the simplest method that works for my machine, and works every time. Whether it will work for your particular machine I can't say. Also, keep in mind that when my machine is plugged into the external display the lid always is closed.
- Wake the display. (I usually untether my machine from the external display in the morning, after the display has gone to sleep on its own because of my non-use.)
- Select "Sleep" from the menu, and wait for the light on the front of the machine to start pulsing.
- Unplug a USB cable from the machine, but not the USB cable sprouting from the "omni"-cable connected to the external display. (In my case, I disconnect the USB cable tied to B&W's MM-1 speakers.) (Note that this will wake the machine from the sleep you just forced it into.)
- Unplug the USB cable connected to the external display.
- Unplug the Mini DisplayPort cable connected to the external display.
- Wait for the machine to sleep. (It will do this on its own because the lid is closed.)
- Wave a rubber chicken and count backwards from seven.
If I do all of that, my machine always is responsive when I open the lid.