Send me your board (just the mainboard, nothing else), Loren, and I'll hack away at it. It could really be just about anything on the peripheral bus that gives that behaviour. I can probably isolate the fault with some effort, but note that I don't have the right equipment/skill to replace the quad flat packs here -- if it comes to that, you'll need to farm it out elsewhere (or perhaps it will motivate me to get a hot air station for such jobs..).

Cheers