Possible workaround for blank screen after sleep
Possible workaround for blank screen after sleep: "I'm sure that many of you with PowerBooks and iBooks have, on occasion, opened your lid only to find that the screen remains black rather than offering you a login. In the past, this has led me to do a forced shutdown. However, I think that I might have found a workaround.
Rather than pressing and holding the power button for the forced shutdown, just press it once briefly, then press S. If you try this whilst your machine is running normally, you will see that, first, the Restart - Sleep - Cancel - Shutdown dialog box is displayed, then pressing S selects the sleep option and the machine instantly sleeps.
I have tried this a couple of times when it appeared that I was suffering from the 'black screen of death,' and I have recovered without further problems.
(Via Mac OS X Hints.)