This is so frustrating... I first had the problem when I had the ACD hooked into my PC. I saw a 2" wide bar of horizontal, rainbow colored lines on the monitor. This got worse over time, and I just assumed it was my PC. I then plugged it into my 17" MBP and, after a while, the same thing happened. When I unplug the DC plug from the power adapter, it gets better for a bit and slowly returns to the glitchy state. As of right now, I am having trouble recreating it. I see an occasional horizontal LINE, but not what I had before. This has all occurred in the last 2 hours. Could it be a faulty power adapter? This is really frustrating because I can't be sure that I will be able to recreate this for the Apple store associates. Help!