I'm sorry! I was mistaken!
I had a few more minutes, and I've isolated the problem. The a/v jack doesn't change anything. I'm actually really glad that's the problem, because I might be able to help fix this one on my own.
I have a Hip Gear LM445 controller. That's the culprit. If I use a standard x-box controller-S, it's happy. If I plug in the Hip Gear, it dies a horrible horrible death.
I was shocked to find out that you guys have SDL keyboard support working. I got to actually *PLAY* Star Phalanx on the x-box!!
You have no idea how easily this has made my day.