The solution? Avoid driver v267.52 like the plague -- especially if you intend to overclock your GTX 590. Nvidia has released a new driver (v267.85) with improved overcurrent protection and SweClockers has confirmed that this solves the problem. It may be common sense, but Nvidia says that anyone who's overclocking or running stress tests should use the latest driver available on the company's website instead of the disc-supplied driver, which is inevitably outdated.
Although driver v267.85 has enhanced overcurrent protection, Nvidia notes that it's still risky to raise your card's default clocks and voltages. The company recommends leaving the GTX 590 at its stock voltage when overclocking with air cooling, while folks with liquid cooling should remain within 12.5-25mV of the default voltage. Nvidia believes SweClockers pushed the GTX 590 beyond its limits by running it as high as 1.2V instead of the default 0.91V to 0.96V.