Thanks for your note, Keith. At least someone else out there has some similar issues, so I’m not completely mad. Anyway, here’s the latest: After some very timely back and forth with Blackmagic support, their rap is that the Mac graphics card (ATI Radeon 5770, 1GB RAM) draws the video onto the Apple Cinema display, and since the video output (which is definitely the BM card, of course) is fine, then maybe it’s not the Blackmagic card after all.
To BM Support’s credit, we did go over drivers, other apps that might conflict, etc. The tech I worked with was very helpful. For a while it looked like the onboard Matrox CompressHD board might be the culprit, but no.
So, we’re still where we left off, in terms of frozen monitors. This does happen in multiple rooms, with the same shared footage, the same rev of Avid, the same kind of CPU/gfx card/BM hardware, so I just don’t know what could be causing the problem. Anyone else have issues with Radeon 5770 cards in a Mac running Avid?