Evil Kraig F, GSquared, both good points.

I let the task run all night, came in this morning, and it still did not complete. However, I did notice this in the execution results:

[blah blah blah[1]] Error: The attempt to add a row to the Data Flow task buffer failed with error code 0xC0047020.

So it looks to be a buffer error of some kind. I'm still researching a solution.