So, this is a long story issue if I've get it right. I'm trying to isolate the problem and hoping hoping hoping that this is not an hardware issue. Randomly the screen stay black after going in sleep mode, the computer seems to continue working and spinning, this is not happening if I touch the keyboard just after that it goes to sleep. The problem happens often, I'm not absolutely sure but this seems to be started after 10.9.2. I'm now installing the new CUDA update, maybe this could be related. Until now I have hard restarted it, now I've discovered that restarting with ctrl-alt-power works as well. I'll try to understand if resetting pram/smc etc can help me. edit: all done, I'll wait. I cross my fingers for the logic board (I'll do the hardware test if nothing help me), cross them with me TLDR: Are you experiencing a lot of black screen after 10.9.2?