Since we never determined exactly what the cause was, why don't you just use the two sets referenced in the test they are readily available at RDNA and we have their permission to share them if it helps solve this problem. We did a LOT of testing of the obvious such as what you are suggesting, but could not isolate a single factor in the light sets themselves other than it appears spotlight related. It seems to occur during the update (data refresh) process in P5. Lights themselves are not the only cause of the lock-up. Applying textures via MAT pose files (or even switching them in the material room) will cause a very similar lock-up under the right circumstances. Ultimately we suspect that it is a refresh process that is not purging old data after loading new data, causing source-call conflicts at render time. Most of these problems do NOT show up at the time the texture or lighting switch is made, but only on the first render after the conditions are met.