回答“iMac27 crashes to black screen, fans running, won't boot for a day”iMac 27 2.93 i7, 16GB ram. Screen goes black randomly after Lion upgrade 10.7.3. This issue just started for us about a week ago, and i finally found a quick solution to avoid a restart after a blackout. When it goes black the CPU and system is still running, but can't do anything without force restart. Mirrored monitor stays on and i can work, but its a pain. The blackout is intermittent and i can't recreate the issue. Have restarted, Reset PRAM, SMC, prefs, privledges...everything. This worked for me to get the screen to come back on without restart: Shift+Control+Eject key. This forces the system to switch back to the inegrated graphics and not the nvidia drivers, which is causing the blackout. http://reviews.cnet.com/8301-13727_7...ck-screen-bug/ This fix has worked about 10 times now. Hope this is addressed soon by Apple, it's got to be a hardware issue!