Don't suppose you've flashed the BIOS with a custom BIOS anytime have you? Might check the ABit website for the most up-to-date BIOS and flash it. I had the same crap happening to me, BSOD's galore when I was using a custom BIOS, even during trying to copy windows files. A Flash back to manufacturer BIOS fixed it, then from there I was able to go back to custom BIOS's.
Even if you aren't using a custom BIOS, perhaps getting the latest one will help if the RAM is not erroring in memtest or anything like that