Really frustrated with this...on occasions when I "awake" my MacBook Pro (2011 with OS Lion) from idle state a black screen comes up with the spinning wheel. Its not possible at all to get rid of it without holding down the power button. Its an absolute inconvenience. This doesn't happen all of the time but has me worried. I've noticed that while the black screen is there and if I use gestures on the trackpad, so for example to move the view to dashboard I can see everthing I was looking at behind the black screen but as soon as I remove my hand from the trackpad the screen returns black with the spinning wheel!! Any ideas please!!???