Graphics can't handle shadows

I have Need for Speed Most Wanted, and Quake 4 for my Mac, and i have noticed that whenever i'm playing the game, and if there's a shadow on the road when i'm racing in NFS, it turns out completely black, and you can't notice any detail whatsoever. The same is with Quake 4, and i have the settings set to the max on both games. My graphics card can easily take it, it's the Nvidia GeForce 8600M GT 512 MBs. Now i have Bootcamp running with XP, and i have Crysis, Frontlines: Fuel of War, Bioshock, and Call of Duty 4 all installed, and they have the same settings, and the shadow detail is excellent. Crysis i do have set to medium, but the shadows are still excellent. What can be the problem with the Mac partition?

I have the same exact problem for Need for Speed: Most Wanted. If anybody has a fix for this, I would hump them.

Crossover

I got this enabled on my mac using Crossover.
1.Download CrossOver, then open it
2.Then at the top, click on configure,then manage bottles
3.Create a bottle by clicking on "+" on lower left hand corner
4.Name your bottle, then in "New Bottle Type" choose which one you want, i chose "win vista". Click Create.
5.In your bottle,click on "Applications" the click on "install software..."
6.A window will open. At the top there might be a yellow bar, IF IT DOES, click on "Update Now".
7.Now in that same window,search for "DirectX".
8.Then click on an option titled "Runtime Support Components", You will see DirectX 9.
9.Install it
10.Then once it installs, hit "Done".
11.Now in finder, go to Need for Speed Most Wanted and right-click on it. Then click on "show package contents".
12.Click on contents, then resources, then transgaming, then c_drive, then program files, then Need for Speed Most Wanted.
13.Then look for "speed.exe" and open it. The game will start.
14.Now in options, got to video, then you'll notice shadow detail is enabled
15.Ok, enable shadow detail, but once you, a program error will appear, click close, and terminate process. Now reopen "speed.exe" then in the game, go to video and you'll notice that shadow detail is enabled again, but this time there is a yellow bar next to it, like the rest of the other options. Then go to free roam and shadows will look better ;D