The fixes I recommend are the xbox service from MSFT or finding a refurb on newegg.com or geeks.com
My XBox 360 has been working flawlessly for about 3 years. The other day I put a Netflix movie and shut the xbox down from the dvd menu screen. I turned it on later and put a game in and I only received sound with diagonal green and purple lines in a full screen format (it is setup to run on an HDTV). No red rings either.
Any ideas on how to fix this? Thanks.