Xbox 360 is showing purple lines on tv screen.

well definitely video issues of some sort. if you have a second video cable (or hdmi cable if your unit supports that) give that a try.
*assuming that doesn't work Unfortunately it sounds more likely that it's an issue with the video card inside the xbox. this may be repairable by a professional.
if you have it under warranty i would contact microsoft for a replacement/repair https://myservice.xbox.com/en-US/Pages/Welcome.aspx or call Toll free: (800) 4MY-XBOX
~best of luck!

Your GPU is losing the connection with the mobo. You're about to get RROD.

ok use it

ONE THING YOUR CORDS ARE WACKED OUT AND THE COLOR DISTORTION SIMPLE NOT YOUR XBOX IT IS YOUR TV

Follow the steps below, Hope this helps

1. Try another Av cable ( Audio video Cable )

2. This issue is caused by the video card inside the xbox 360. If you still have warranty better send it in for repairs ( Call xbox customer support )

Good Luck

this happens when your xbox overheats. its happened to me a few times too.

rate

Wow i have no idea what to do with my Xbox #360 Elite. I was playing halo3 and my screen started acting up, and the colors on the tv were flashing.. red pink green and blue.. but i could still play.. so i shut it down then turned it on and had no picture

I have noticed my 360 shows blacks as purples now on the computer monitor I have it hooked up to through the HDMI cable and I have the elite system. I have yet to hook it up to my tv and so far the only game I really can it see it on is Frontlines: Fuel of war

I had this same problem. What happened to me was that I mixed up the color coding on the tv cables. You can try to check if you did this. If not, call the help line on xbox.com.

Is the tv rated for HD? if its not the inputs will be at a wrong voltage and will create that snow like effect.

Is the TV you normally game on HD?