The first thing I would do is disconnect the DMX, does it happen when it is not connected? if it doesn't I would recheck the values to make sure that nothing has been double patched or check to make sure the brightness and colour pins are all at 0 when this happens. I often find that watching the zookeeper when it happens can help to figure out what is causing it. If it still happens without DMX we will need to re-look at what is causing it.
Thank's for the quick response. I was not at the venue myself. But was told that the whiteout was not only on the output, but showed up on the zookeeper overview as well, and was totally random. They rebooted the Hippo and that seemed to solve the problem. (Without changing anything on the programing) Just wanted to know if anyone else had the same experience. And if so, if it was a sign of hardware wear.