I’ve had this happen a number of times, but haven’t been able to recreate it or find a common thread in the situations that could help me troubleshoot. I’ve repaired permissions, trashed prefs, restarted, rested my drives. Nothing seems to eliminate it completely. I also have a Blackmagic card, but I’m not always using it.
Recently, I captured some clips via the Voiceover tool. Once all the clips were in and I started editing them I was getting these loud screeches randomly on one of the clips, but not on any of the others – to the point where I had to trash the clip. I never bothered recapturing it, but it made me think there was something in the clip triggering a glitch rather than it being a random hardware or software issue.
I’m keeping an eye on this thread to get to the bottom of this. Like you guys, it’s the closest I’ve ever come to smashing the computer.