Dishwasher cause electrical interference with HT

Perhaps someone can explain:

In my dedicated audio room on the third floor of our house (which also has a front video LCD projector) and DVD player, I have 5 dedicated circuits that were installed during the construction. The electrical supply for the whole third floor comes from a subpanel which feeds back to the main panel in the basement. The five dedicated circuits, have 10G inwall wiring with supposed isolated grounds that go back to the main house ground (water pipe). For the first time in the year that we had the room, I was watching a DVD movie (both the DVD player and the projector are connected to one of these dedicated circuits) and I noticed white horizontal interference lines and breakup of the image. I went downstairs to tell my wife there was a problem, when I noticed the dishwasher was running (connected to the main panel in the basement). When the dishwasher was turned off, the problem seemed to go away. I don't know if the dishwasher has ever been on before during a movie, but this is the first time I have noticed the problem.

Any ideas why this should happen with this set up and is there anyway to further isolate the dishwasher circuit ???
Make sure the circuit breaker for the dishwasher is on the bottom of your service panel and the HT circuits at the very top nearest the incoming power line.
That would be your first line of attack, however you might try parallel line conditioners like the Audioprism Quiet Lines or the Blue Circle units.