I have been having major problems with my Vive Pro for months. Losing vox, losing sound, grey screen and freezes...all happening randomly after a few minutes play. I was also getting an eardrum bleeding screech from time to time.
I was trying every setting permutation possible in SteamVR, in Voice Attack and AH3. Nothing seemed to fix it.
This may seem obvious, but I did not know that "Shut Down" does not mean "Shut Down" in windows. It retains any bad setting you have. You have to "Shift+Shut Down" to get a real shut down. Maybe everyone knows this' but I didn't. It clears all the crap you have otherwise retained for hibernation and a faster start-up..
That seemed to help, but I also discovered on YouTube that Vive does not like the USB 3.0. It needs to be connected via USB 2.0.
Since doing both. No problems.
I hope this saves Vive users the grief that I have gone through.