Return to Castle Wolfenstein

I just bought the wolf pack off Steam and this game was included. I installed it, but when I try to play it, it stops working. It checks for solutions for a few seconds, then quits. I never get any options besides cancel. I use Windows 7 btw, and it's not a crappy PC. Why can't I run this game?
---
Now that I think of it, Petey just kidnapped two princesses at once! He's the man. ~Socran

All my drivers are updated. How do I run in admin mode? I thought I was in admin mode because my computer only has one profile. I don't know what mode I'm running in, so how do you switch?
---
Now that I think of it, Petey just kidnapped two princesses at once! He's the man. ~Socran

No such thing appears when I right click. However, a strange thing has happened. Only when I open it from steam, it gives me the option to run either multiplayer or single player. If I choose single player, I get the same problem as mentioned above. If I start multiplayer, it actually runs and I get the multiplayer options. But when I try to switch to single player from that menu, it still stops working. Any advice?
---
Now that I think of it, Petey just kidnapped two princesses at once! He's the man. ~Socran