XBox 360: Third Time’s the Charm?

My XBox 360 is broken. My first one broke on Christmas Day in 2005, and the second one broke just a few months ago in March. First one was three rings, 2nd one was a bad drive. This time it's something new.

It's actually a problem I haven't heard of before. The component video output is on the fritz, but not completely. The picture is there, but it's got a lot of fringing and coloured sparkle on it, and occasionally the picture jumps like it's losing sync. It seems to be getting worse, so I expect it will lead to failure before long.

My 360 is sitting by itself on top of a cabinet so I know it's not an airflow problem. I wonder why I'm having such bad luck.