There's no one factor. I wish there were a silver bullet we could point to and say, gee, if we only fixed that, we would solve all of our problems. Clearly reliance on a weak currency for a long period of time--the fact that we've relied on the dollar at 70 cents or lower--created a form of a crutch for a lot of our economy. People came to expect that to be normal. With the tremendous run-up in global commodity prices, that's driven the dollar to sky-high levels. So there's an adaptation shock we're going through right now.
On December 13th, 2007. See this statement in context.