I was just playing the 360 and then everything froze up. I turned it off and turned it on in about 1 hr then I had 3 rings of red. Top left, bottom left and bottom right.
Does the PSU have a red light on it as well? I got the RROD a while ago, but it turned out to be the power supply that was faulty. I replaced that and it's been fine ever since. It's more than likely the console that's broken, but it's worth a look.
Also, you can hold the sync button in on the front of the console and hit eject. A number of lights will flash on the ring of light: -
Look how many lights are flashing and while holding in the sync button, press eject a further 3 times, paying attention to how many lights flash after each press. That should give you a 4 digit code which you can use to narrow down what's wrong. In my case I got the code 0003, which is a power problem (caused by the faulty power supply).
If it's under warranty (3 years for the RROD) and it hasn't been tampered with, you can send it to MS to get it fixed for free. If the case has been opened for any reason, you could send it in and hope for the best, or you could try one of the fixes available on the web that seem to work for some people.
Though it's most likely GPU related literally means the console does not know what is wrong. possibly a short or cold solder joint somewhere. So far there is 1 major theory for what causes most of these errors is that the Ram, CPU, or GPU are not soldered properly to the mother board due either to poor manufacturing or excessive heat up and cool down cycles that stress, weaken and eventually break the soldered connection.
There are two theories to fixing this one deals with the "X" clamps that hold down the chips. The other involves re-Heating the chips. DO NOT attempt either of these if your console is still under warranty. If your console is still under warranty return it to the store where it was purchased or call MS to have it replaced. I have also heard of limited success by simply switching the AV cable from "HDTV" mode to "TV" mode.