I am completely unable to get past the game launcher. It pulls up fine, but when I click play, it get a popup asking if i will allow it to make changes to my system, I hit yes, and it disappears, then the loader pops back up a second later. Sometimes the launcher never comes back, it just disappears. When I validate game files on steam, it always says 1 file could not be validated.

I have tried every 'solution' i could find. i uninstall/reinstalled the game, updated all my drivers, tried every combination of gfx settings i could think of. Any suggestions would be great.

core i7 2.4ghz
2x ati 4850 in crossfire
4gb ram
realtek HD audio (R2.53 drivers)