I have experienced this countless times and video taped it where the system freezes and all the keys and trackpad locks up but the music continues and I must hold the power button to turn the computer off.
Does anyone with legal knowledge know whether or not their are any legal ramifications seeing as Apple does not allow you to downgrade and consequently entrap their users on this new software. More importantly, their customer support are not acknowledging that it is a software issue by placing the blame on the customers. So if it can be proven that it is their faulty software, either they must allow their users to downgrade with apples permission or they refund the product. I wonder if the lemon law could apply for all of these users?