[Eric Westfall]

Running Pro Tools 12.4 on a 2010 iMac, 30.06 GHz processor. No audio interface, I simply output from the headphone jack to speakers (which I really like the sound of). Mixing for a client who brought in a project recorded at 96k. Mixing proceeds smoothly for 5 or 10 minutes when a loud crackle, followed by loud beeps in groups of three. Computer freezes.

I suspect a sound card issue in the Mac, but clueless what to do about it.

Thanks for any help.