So, updated to High Sierra Public Beta today, and everything works like a charm - Except Firefox. No sound at all. Plugins updated. Music from itunes and all other apps work fine. Tried downloading a different version of Firefox and same result. A video from youtube plays, but not the sound. Rebooted machine several times. Reset NRAM (or was it VRAM?) by holding option+cmd+r+p. Same result. Anyone had a similar issue? Suggestions? EDIT: Safari works fine. Seems Firefox has an issue with High Sierra.