Arkham Asylum .NET Framework error

I recently got the PC version of Arkham Asylum for free, thanks to an NVIDIA promotion that was running when I bought my video card. I figured I'd download and play the Arkham Asylum demo to see what the game was going to be like. So, I downloaded it off of Steam, and tried to run it. It instead gives me the following error:

Code:

Unhandled exception has occurred in your application. If you click
Continue, the application will ignore this error and attempt to continue. If
you click Quit, the application will close immediately.

Value was either too large or too small for an Int32.

It then dumps this debug info on me.

Hitting "Continue" brings up a buggy menu that has the game logo on it, and outlines for what appear to be buttons. There is no text, however. Clicking on the topmost, bigger button gives me another error, the same as above (this time titled "Batman Launcher"), but instead says "Object reference not set to an instance of an object." It gives me this info. Hitting continue just makes the launcher look worse.

So, I think this means I have some sort of .NET issue, but I'm not exactly sure what it is. I have the .NET Framework 4 installed, but maybe I need to have older versions installed, as well? I'm not sure.

See the details in the following link....NET error (Value was either too large or too small for an Int32) - Eidos Forums