I just installed the Mac Pro EFI update, and after it shut down and restarted...when I got back into OS X the screen flickered one and off...like there's be a 3 second gap, then it'd go black, and it kept doing that. I'm using a Samsung 225bw with the DVI cable that came with it. I don't believe the cable is related though because I didn't have this problem when I was using this same monitor on my Dell. The cable is on securely, so I don't think it's that either... This has happened a few times before...usually after a shutdown. Any ideas what could be wrong?