NEW YORK (CNN/Money) - Draw a nice long historical chart of commodity prices and the rate of inflation and you will find, unsurprisingly, that the two rise and fall together. Until now, that is.

Now we're faced with the odd world where the prices of raw materials have risen sharply for two years, pushing the Commodity Research Bureau's index of commodity prices a smidgen short of its all time highs, and yet, inflation, as measured by the consumer price index, is remarkably muted.

You can come up with all sorts of reasons for this odd divergence. There's growing demand for raw materials from China, which, thanks to its low production costs, turns them into cheap consumer goods that get shipped back here. There's a huge amount of excess production capacity sloshing around at U.S. companies making finished products, while manufacturers that work at the initial stages of processing are running remarkably tight. And then, there are U.S. consumers, who despite their enormous propensity to spend, simply refuse to pay higher prices for many goods.

Whatever the root causes, however, the final effect is the same: Between rising commodity costs and consumer prices that are barely budging, many U.S. companies risk seeing their profit margins ground to a fine powder.

Take the auto industry as an example. New car prices fell 2.1 percent over the past year, according to the most recent CPI report. But the base cost of many of the things that go into a car has risen, as has the cost of the energy it takes to build it. Or the clothing industry: apparel prices have fallen 1.9 percent, while cotton prices have surged.

Some people reckon this isn't a problem, because such costs are minor compared with firm's major outlay -- wages and benefits. Many companies have been able to more than offset rising commodity costs, for instance, by shifting healthcare costs onto workers.

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But aren't workers who see their real earnings power decline eventually going to demand higher wages? And if their earnings power stays low, aren't they going to be less willing to buy stuff? We all remember the old story about how Henry Ford wanted the wages he paid high enough, and the cars he sold cheap enough, for his workers to drive around in Model As.

If U.S. companies can't figure a way to raise prices soon, their earnings could get stuck between a rock and a hard place.