Xbox 360 Bottom right quadrant light?

Okie, a couple of weeks ago after about 1 hour of playing Call of duty, my screen went crazy. It had vertical purple and red lines and when I restarted my console it worked fine for the rest of that day. It started happening again after just a couple minutes. I looked it up on Xbox support and it said one thing to try was to reset the display settings. So, I held the right trigger and Y, and when the Xbox reset, I had the error code E74 at the bottom and the bottom right ring was illuminated red. It said to go to xbox.com/support in like 20 languages. I tried disconnecting everything, including my harddrive and other hardware. It still gives me the same code after 2 days. My Xbox also has no warranty left, and it's not my A/V cable. Am I screwed or is there something else I can do?