Finder Dock Icon Distorted

I'm a new Mac user. I just got a MacBook Air a couple days ago and I love it. My problem is that after installing a game (Civilization IV) the Finder dock icon has become distorted. It's not a graphics problem, as far as I know, because nothing else is distorted on the screen and the rest of the dock is perfect. So my question is how do I fix this. I've inserted an image of the faulty icon below.

There's no image.

It's very possible that this is a minor glitch that can be resolved by restarting the Dock. Open up the Terminal (/Applications/Utilities) and type the following: The Dock will restart itself.

Tried that....

Thanks so much for your reply. I tried (I also tried it again) that already and it is still distorted.

I also checked the Core Services folder and the Finder con in the folder looks perfectly fine, though I'm not sure if it is connected to the dock icon...

Screen Shot 2012-01-24 at 3.11.51 AM | Flickr - Photo Sharing!

I tried that before and it didn't change anything. I've also checked the CoreServices folder and the Finder icon there is not corrupted, though I'm not sure if that is at all related to the icon on the dock (I read somewhere that it was).

Screen Shot 2012-01-24 at 3.11.51 AM | Flickr - Photo Sharing!