I wondered about this too. I have no problem playing any of my other games, and a couple are pretty graphics intense. Only other odd thing I have noted, is that sometimes after quite awhile working on the comp, it will just shut off and not restart for some time. I'm assuming this is a temperature problem. Even with 2 case fans, double RPM fan on the processor, and one on the video card heat sink as well, I'm still running over 90 degrees inside the case and 110 degrees at the processor. All of this tells me there is a possible heat problem to deal with, but if thats so, then why did this setup work fine to play AHII just days ago, but now it wont? The way I see it, one of three things is happening, and I'm just fishing to see if anyone is experiencing, has experienced the same thing, and what worked or is working for them.
1. Coincidence. Something unrelated happened at the same time I was performing my video card switch-out and switch-back that is totally unrelated and just happened to come along right then. Has nothing to do with either video card, the drivers, etc.
2. When I installed the new video card and installed the drivers for it, something in my system changed and I dont know how to change it back. I know for a fact the current card, with the current drivers worked in AHII up to 2 days ago (this was after the beta ended). I know I have scourged my computer of any reference to the drivers that were installed during the swap-out and even my registry has been cleaned of references to that card and/or its drivers. I know that I have uninstalled, and deleted all the folders for AHII and done a clean download and install. And even after all this, and using a card and drivers that worked before, I am having the same problem I had when I first installed the new card.
3. In the process of installing a new card with new drivers, and then uninstalling it, purging my system and reinstalling the old stuff, something changed the way the computer (or at least AHII) sees my video card, and now that whatever old setting WAS there is gone, it will never work again. I see this as highly unlikely, since plenty of other people are using the same processor family of chips on video cards (nvidia geforce4) successfully. Even if the game never saw my card the same again, it should still run.
I am looking for clues. Anyone with similar problems who solved them, or someone who helped someone else solve a similar problem, someone who sees something obvious I missed, etc. Thanks for any help anyone can give.