I searched and hacked, and removed all my touch event listening code, and it would still break. Luckily the company work for has the resources to invest in development, and we went out and got a Samsung Galaxy S phone. I set the device up, published the app, and this phone did not have the cryptic issue! It did, however, show a range of other issues with fonts and the <canvas> object, which made me sad, as it's clear that building an HTML5-based app for Android isn't as easy as I hoped. The fragmentation of the Android platform is definitely an issue if you're attempting complex UI design and interaction with HTML/Javascript. I recommend keeping your HTML5 app very simple if you're targeting multiple Android platforms. Even though all new Android devices use Webkit, there are plenty of small, ugly differences.
[UPDATE]: The following code, when removed from my project, got rid of this weird error:
document.ontouchmove = function(event) { event.preventDefault(); };
Another update... Check out this post, and try out the demo code to get a bit more idea about how to handle preventDefault() on touch events in the Android browser: http://code.google.com/p/android/issues/detail?id=4549. It still crashes on my HTC device, but works great on the Samsung device.