Over the last year I have been fighting with a rolling video line issue with nearly all of the K4’s I have installed since the product first came out.
I have also had trouble with rolling lines appearing on other types of displays in any given system, for no particular reason as long as at least 1 K4 is involved in the video chain somewhere
I tried everything to get rid of it to no avail, Finally I found a low cost video ground isolator, Which gave instructions to the effect that the isolator should be connected near the source. Well that did not work, so I installed it backwards at the k4 itself and the rolling lines disappeared, well actually the rolling lines on every display in the house disappeared.
I though hey this is great, problem solved, the K4 has been dumping a bunch of junk into the whole system and this little cheep part fixed it.
BUT! Then I put the faceplate back on the K4 and the lines came back worse than before, I thought what the hell is this, so I took the cover off and the lines went away on all of the displays again. Then I put my thumb in front of the light sensor and the lines came back, so I grumbled how stupid is this. So I deactivated the light sensor in the software and whole thing works great.

Obviously there is something seriously wrong with the K4 light sensor circuit that is leaking junk into the video circuits, I have one system that was so bad that you could see red hash visibly appear on a Samsung DLP every time you executed a command for the K4.

Note that just turning off the light sensor does not solve the problem; you have to turn off the light sensor and install a video ground loop isolator.
I found the video isolator here [Link: 2mcctv.com]