This is just FYI: Have had my MBP refuse to wake up several times. Happens randomly.

Have sound when hit space key - can hear hard drive working - but black screen - have to do a hard shut down and re-boot

Discovered issue is related to shareware installed that has a pop up basically asking Buy Now or Continue Using. During the process of waking up, this pop up starts prior to the screen being turned back on. This third party software then halts the start up process until you click one of those selections. And of course, you can't see the screen to click on it.

For sure the following shareware causes this issue: Steermouse and the Unsanity products - Shapeshifter, etc.