Getting Interference and Feedback

While I'm playing my 360 I can see purple bars rising up the screen if i'm in a dark area. Also while watching a HD-DVD or DVD I can hear a humming sound that gets louder as I turn the volume louder. I've got the 360 connected with the Microsoft HD Component cables to a Philips HD TV. Same cables are connected to my receiver for sound. My wiring is also all crisscrossed over each other but by the time I finish posting this I'll be starting a clean up. My question is should I start with some Monster Cable sheilded A/V cables, get a Line Conditioner of some sort because all my Electronics (Cable, Computer, DVR, 360 etc..) are all on the same Elec. circuit. Or am is there something else I could also try. Helps appreciated. My TV sits on a stand in the corner of my living room with my Subs right behind it. Could that be affecting me as well.

I definetly thank you guys for the replys. As I am familiar with Ground Loops I'm not as adept at finding a low cost soloution. Since I can't rewire my living room is there anykind of hardware I can by to help out the situation. I did read the link Formulanerd sent and I'll be troubleshooting with those tips as well.