I also having issues with my HD4670, also random hangs up after loading a mission, i hear the sound that is played before take you to the briefing, but its not, it just hangs at the loading bar.
I also having a issue of "white texture" when there is a lighting on the ship because of critical damage.
In my other pc with an X1650 in having the same hanging problems, but not the white texture problem, and are using the same driver... 8.12. Just its Vista x64 on the 4670 and XP32 in the X1650.
Also i getting some wierd and massive slowdowns in the X1650 is too obius, mostly when in close to other ship or facing a big ship, it shouldt be hapening, it just 1024x768 with 0xAA 0xAF...
With the HD4670 i having the same problem... massive slowdowns when im flying too close to a ship (fighter bomber).