Hi stewer, I think I'm gettin to the point. The spot is showing up (y-direction) and is thus placed in a 90 angle to this wall. It is meant to light a completely different part of the hall. It is more than 10 poser units away from the wall (x-direction). So this is just stray light. The pattern definitely comes from the shadow map and no displacement helps. Other spots show the same behavior, but not as obvious as this one. You have to look very close to see it. It also seems that moving this light closer to this wall the pattern gets smaller. I have to verify that. At the moment I assume that there is a bug in rendering the shadow maps. To get this effect you have to place a spot quite a distance away from a wall in an angle to the wall about 90 and a wide light angle (near 160) to get the "best" effect. I will give 'disabling "cast shadows" a try.