Unfortunately, I'm unfamiliar with the video card you have. It's been 6 or 7 years since I've last used a laptop computer. However, two things is all I can think of:

1. Try installing a game that you know has fog. If the game has fog, then there's something weird going on. If it doesn't, it's likely a video card issue.
2. If the item above fails, contact ATI through customer support to see if they can help. Since you're in the USA, you could consider calling them as well (although they may have international numbers to call).

Other than this, I don't have any other option.

Edit: Or, you could also contact the place where you got your computer from. You seem to have a very nice computer (in terms of specs anyway).