I know it's still a demo, so this could be the problem. It says stuff about 70% complete, blah blah blah, almost like it's a partial beta. But anyway, here's the problem...
About halfway though a race, my sound gets all crackly. I guess it almost sounds like my cable is shorting out or something, or rubbing on the case. The game continues just fine, and you can still make out the sound, it's just got that static as well. Once it starts, the only way to get rid of it is to close the game and reopen it.
My system is an AMD T-Bird 1.4GHz using a Sound Blaster Live and running *gulp* Windows XP Pro