sound disappears after game/computer idles

windows 10
MSI MP251 (NVIDIA high definition audio)

no sound problems in any other app.
no sound problem when starting (and playing) the game.

after the game (computer?) sits idle for a while, the sound in POE1 is gone when I come back to the game (the computer does NOT go to sleep while sitting idle).

I have to exit & re-launch the game to get the sound back.

(this may have started around the time that I did my last NVIDIA audio driver update)

thanks!

helm