I wouldn't system restore. Things can get messy in your registry if you restore too often. If it happens again, go to Alienwares tech support site. You'll be able to select your M14x and it'll show you the latest audio drivers. Download and install the latest audio drivers before restarting. This should fix the problem, even after an update.
And ya I understand about BF3 being too expensive. I'm holding off on the Premium expansion pack until they lower the price (Just a matter of time). I think I bought BF3 on Black Friday with an Origin birthday coupon for $29