No One Lives Forever 2: A Spy in H.A.R.M.'s Way

Rating:
Summary: Excellent Game, but i need help with something...
Review: This game rocks! I played a demo like 2 years ago and i loved it..

I'm having trouble when i try to play in single player mode. Just before it starts in single player, it sends me to windows. I have it since 6 hours and only be able to play it in multiplayer... Please help me!!