Y'know, the intro 'movies' you get after choosing marine, predator or alien. I know it has nothing to do with my hardware, because I could run the demo just fine on high / very high settings. HALP. I DUNNO WHAT TO DO *sadface*
___ Would you kindly get stepped on by a Big Daddy?
Your only solution is to launch it under dx9. My setup is windows 7 and a gtx 260 card(dx10). I don't think anyone knows 100 percent what's going on but some dx10 cards can run AvP under dx11 and some cannot. You are under one of those unlucky people with dx10 cards that can't run it, don't feel bad because I can't run dx11 too.
Fix for 5850 ATI video card would be to download Catalyst 9.12 drivers from ATI. You have to uninstall the latest 10.1 driver, then reboot, install 9.12, reboot and try the game again. That fixed it for me.
Not sure about Nvidia cards right now, probably need a driver update or try a different driver version.