Actually, video wasn't my problem, it was audio. The AC3Filter I have installed was causing it to crash, and even spontaneously reboot my computer after clicking the 'New" game button. I hadn't realized I had left the Filter selected for not just AC3 audio, but PCM, DTS, MPEG, and PES. Once I unselected those, its worked beautifully.
My video card is a Powercolor Radeon X800XL VIVO, and the HDR option is greyed out for me as well. I believe your card has to support Shader 3.0 to be able to use HDR.