I have the same problem. I got a notification from Parallels to update, so I updated, but immediately after that, Windows won't start up and it's stuck on a black screen. CPU usage is 100%. When I click on the black screen, the mouse stops working and the base Mac stops working. I can regain control by pressing and holding the power button, which makes the Mac respond. Action-Reset, as suggested by Parallels, doesn't improve the situation. I think the staff should think carefully instead of just making cliched suggestions. I don't think this is an easy problem. It's been a while since this thread was posted. I think I need to contact you no matter what the situation is. I'm in trouble, so please do something about it.