Just happened to me again.
I think I’ve been getting it when there’s been quite a lot of things going on at once. Like a boss fight with heaps of particle effects or WvW. But I think it’s also just happened randomly too when there hasn’t been much going on.. but still something.
Hard to pin point but I think it’s to do with many different sounds at once and the sound drivers crash and go into like a ringing alarm mode. Quitting the game automatically stops it and then you can log back in fine.
I’m going to try updating all of my sound drivers and see how it goes. If it happens again, I’ll record it so we can verify it’s the same sound we’re all getting.