Question 1: Is the player running firmware version 2.x?

Question 2: Does just the *car* sleep outside, or does the *player* sleep outside with the car?

If answer 1 is "No, it's running 1.x", and answer 2 is "Yes, the player sleeps outside with the car", then yes, your problem is the player is too cold and the hard disk isn't spinning up. If you were running firmware 2.x, instead of just freezing up you would have seen No Hard Disk Found Contact Support appear on the player screen.

If so, then just take the player inside with you at night.