Lights cast weird shadow lines on walls when I render in Vray

Apologies, I mean the lines on the walls. Those strange bands that get tighter as you get nearer the ceiling. The wall is a solid colour so I’m not sure where they are coming from. When I switch off ‘shadows’ in the lights, they vanish (but I lose my shadows).

I’m in the process of running a render where I deleted all the individual lights and just created one big rectangle one in this room, and yep, they are appearing again as I speak.

I saw someone else on this forum had the same problem, but there was no answer so I opened a new topic.

The exact same weird lines on their blue walls.

Any help would be most awesome.