Reverb G2 Goes to Black screen

Visuals suddenly go completely black and stay that way for 30 or 40 seconds. Starts towards the end of the game for short periods but becomes so bad I am unable to get past the strider attack on the base with audio around me but completely in the dark! Thus I can get no further in the game.. Visuals continue on monitor screen. Seems to be associated with action scenes, but only on Half Life 2 Episode Two VR mod. All other games play well. Gear is: HP Reverb G2 with later issue cable, MB MSI X570-A Pro, 32 GB RAM, CPU AMD Ryzen 9 5900X, GPU MSI version AMD Radeon RX 6900 XT. with VR games running from 1TB SSD. As said previously has only happened on this game. Just as a matter on interest, I am 78 next birthday (June): amI the oldest player? (!) Thanks for your brilliant work.