Scary Computer Problem in Alamy Quality Control and technical talk Posted November 25 I was glad to come across this thread as I have been wrestling with the black screen problem over the past few days. I don't want to speak too soon but I may have solved the problem today after reading this fellow's article: https://www.macworld.com/article/3209746/imac-screen-blackout.html My iMac is 2009 I believe and has been working perfectly till this occurred. So with a small brush attachment to my vacuum cleaner I hoovered the mesh filters along the bottom of the screen which seemed to have gathered a lot of dust as suggested in the article. I will post here if this isn't the solution but so far it has been working all day just fine. Fingers crossed.